‘have a great running Saito 56 that I would love to get into the air. A profile would be a quick way to get air born. Not to mention better then investing a hundred and $omething in a “test” model.
But the Saito is kind of a porker at 16 ounces. The CG would be right at the glow plug if I made a direct swap from a typical 10 ounce motor. Handling would be sort of like running around corners with a wheel barrow full of cement. My initial solution is to shorten the nose (at least) 1 ˝ inches. Using engine weight X inches from CG to glow plug….. means adding 6 ounces to the engine weight, means a lot of length to reduce.
 
However the Saito is not only a l-o-n-g motor but it has the CL venturi sticking out the back with the fuel nipple pointing directly out the back. All this really uses up valuable fuel-tank space. Just shortening the nose and mounting the Saito leaves room for about a small-ish fuel tank. Which is wonderful for practicing take offs and landings, but little else.
My solution seems to be shorten the nose and mount a Sullivan plastic clunk tank on the inboard side. This actually solves the front-to-rear space and helps resolve the problem of the fuel nipple pointing directly rearward (into area that could normally hold the fuel tank).
Right now I am thinking about a “Doodle Bug” because it already has a l-o-n-g nose to begin with.  Plus I made an extra set of ribs & a extra stab/elevator, last time I built one and already have all the other necessary wood in house.

Using the recommended fuel and prop, after 15 bench runs (4 ounces each) The Saito 56 burns just under 1 ounce a minute. Which means I may need at least 6 ounces capacity, and maybe 7 or 8.

The question is…………. Does anyone have any thoughts on inboard mounted clunk tanks on profile models?

It will work great.. Both my 56's and one 62 use 4 ounces for the pattern. If I were going to do what you are planning I would use a Hays (only because they are easy to plumb) 4 ounce tank on the inboard side. Muffler pressure to the top vent, drill out the middle vent to use it for fueling (plug for flight). I have this exact setup except for a 3 ounce tank and Saito 30 on a profile and it works great.

Hope that's a big “Doodle Bug”, I'm flying 680 - 690 sq/in airplanes with the 56.

Right now I am thinking about a “Doodle Bug” because it already has a l-o-n-g nose to begin with.  Plus I made an extra set of ribs & a extra stab/elevator, last time I built one and already have all the other necessary wood in house.

Using the recommended fuel and prop, after 15 bench runs (4 ounces each) The Saito 56 burns just under 1 ounce a minute. Which means I may need at least 6 ounces capacity, and maybe 7 or 8.

The question is…………. Does anyone have any thoughts on inboard mounted clunk tanks on profile models?

   WOW, that's a whole lot of gas! Far more than anyone else I have seen.

    Bear in mind that the Doodle Bug nose is long for balance reasons - and sticking a Saito on there instead of an LA46 can really screw up the balance.

     Brett