Eric,
Since I last commented on your Bonanza, I have thought about it a bit more and have a few comments/ideas.
First, I think you might want to reconsider making the rear portion of the fuselage any thinner. Even if you reduce the width of the rear fuselage to the 3/4" you mentioned, it will still look like a profile and few, if any will notice. With the experience we have had with the 1/2A multi-engine profile scale contests here in Tucson for the last several years, I do not think there would be any noticeable improvement in appearance in the models if the rear portion of the fuselages were made more narrow. Yes, these are smaller, generally, than your Bonanza will be, but they still look like profiles. Besides, if you leave the fuselage there to be full 1" wide, there will be a more substantial base to attach your tail section which will be good regardless of how you decide to move your elevators.
You mentioned your thoughts on the elevators and pushrods. I do not understand your comment about making one pushrod longer than the other so that the elevators (or horns?) would not interfere with each other. First, your horns should be in the same location relative to each other on either side of the fuselage. You do not want to introduce anything that would result in some sort of differential elevator movement for up and down control. The elevators will have to be separated by something like 1" anyway when they are in the neutral position so they do not interfere with each other at full up. Then, when the horns are at the bottom of the elevators connected to the "Y" pushrod, there will have to be clearance for those pushrod ends and the horns on the sides of the fuselage. Something to think about.
I mentioned the possibility of using a single pushrod with a single control horn using "Lucky Boxes". It could get a little tricky, but I think it can be done. But for it to work, the pushrod connection to the control horn will have to be on the center line of the model which means that it will have to be inside that rear portion of your fuselage and you will need all of that 1" width allowed for a profile. To do this lucky box thing, special attention needs to be given where the hinge line of the control horn is positioned relative to the hinge lines of the elevators with that dihedral they have. That horn must have be bushed so that it can be fixed to the fuselage. Also, the horn wire in either side of the elevator lucky boxes has to be properly shaped. I have used lucky boxes on two of my 1/2 scale models where the horizontal tail/elevators have a lot of sweep. The horn and pushrod on each of these models is completely enclosed in their 1" wide fuselages using a ball link to connect the pushrod to the horn. It will be a lot easier to explain this if I make a drawing on how the horn and hinge lines and lucky boxes all fit together. If you want to pursue this, I will make up some drawings to help. It would help me if you could send me a drawing to show what those elevators look like and how the whole tail section matches up on the fuselage that you will have back there. As I mentioned, I have lucky boxes and a single control horn on my Swee' Pea which has 100o between the two tail panels which means that there is about 40o dihedral under each tail panel. And there is about a 1" spacing between the elevators when they are at neutral and even though it has a scale built-up fuselage, there is not much more space at the rear end of that thing than what would be in a 1" profile fuselage. Something else to think about.
The wing flaps: One simple way is just have a horn on each flap just on each side of the fuselage with a servo driving a single pushrod with a "Y" in it to connect to the horns. There will be a bit of flexing between the two flaps, but not any amount that should be a problem with your scale airplane. There are two other options to get operational flaps. In each of these options, a single horn can be used and you will need to make a decision if you want the flap horn and pushrod enclosed inside that 1" wide fuselage, or will you want the pushrod and its linkage to the horn exposed on one side of that fuselage. It would be good to know how much dihedral and flap sweep there is in that Bonanza of yours. Each of these options have the advantage that there will be significantly less flexing than the pushrod with the "Y". That pushrod "Y" just allows for a lot of flex between the flaps. This amount of flexing is unacceptable for a stunt ship but for a scale model the size of yours, I would think the flexing would be "acceptable" or at least not creating any trim problems that would otherwise be experienced when trimming a stunt ship to fly the pattern.
1. It sounds like you may need no more than 20o down deflection of the flaps. With this amount of deflection (meaning fairly small) you should be able to use a single horn connecting both flaps. That horn will have to have bushings and mounted to the fuselage to give a solid structure to hold the flap horn and to let it move smoothly. Then attach that horn to the flaps like on a conventional stunt ship flaps or elevator. There is a lot of experience with stunt ships with swept forward flap hinge lines and with semiscale stunt ships with quite noticeably swept forward flap hinge lines and dihedral that have the flaps connected this way and there is no binding in the deflection of those flaps through 35o to 40o deflection up and down. I know that this does not sound like it would work, but it does. I believe there is enough flex in the hinges, in the manner the horn is mounted to the flaps and in the flaps themselves to allow this movement up and down without any restrictive binding.
2. If you are concerned that the combined dihedral/flap sweep angle is great enough so that binding would occur at that 20o flap deflection angle, then you could think about using lucky boxes on each flap and the single horn, sort of like described above for the elevators. There is a bit of a problem here though if you want the hinge line of the flaps to be at the bottom of the airfoil like your drawing shows. An alternative would be to put the hinge line up inside the airfoil with the LE of the flaps being rounded and the TE of the wing contoured to match the flap LE (as in a scale hinge line location). This would look better anyway and would probably improve the effectiveness of the deflected flaps.
More things to ponder.
I hope this makes sense.
Keith