Hey Chris:
How much building are you willing to do? I ask because if you build your own, the answer is "as much spacing as you want". Building a carbon-fiber "Walker" handle is absurdly easy -- you can knock one out in about an hour if you put your mind to it and have the stuff on hand.
Here is a picture of my version of a CF handle, which trades off some overhang for having a closed bar across the knuckles -- this allows me to make the thing out of 0.06" CF plate rather than the 0.10" that Paul Walker uses, which lets me get the weight down a bit. I need to do it anyway, because I generally run much narrower spacing than most people, so the leadouts need to be in front of my fingers. (It's me, not my airplanes -- a friend crashed a plane of mine because I loaned him plane and handle, and we didn't widen the spacing. It sounds like I'm the opposite of you in that regard).
As you can see, the maximum spacing on this handle is 4 1/2 inches -- but you should be able to see that by cutting the frame differently, you could easily make the spacing as wide as you needed. I would suggest that if you go much above 5" spacing, or if you want to use a "C" shaped frame to get less overhang that you go to 0.10" plate: you probably need the stiffness more than you need the weight reduction.
I'm including a sketch of the way that Mike Haverly prefers to make his handle. He feels that having low overhang gives him a distinct advantage, so he optimizes for that. He whacks the frame (black lines) out of 0.10" CF plate, then puts a balsa grip on it similar to mine. (The blue circles show roughly how his fingers fit in the frame, to give you an idea both of how close the fit is, and how personalized the handle is).
If you do go out and make a super-light handle, make sure that you have some extra holes on the inside to adjust to: both I and my flying buddy found that with a lighter handle we were actually overcontrolling in the corners with our "heavy handle" spacing. With the lighter handles we went in a notch on the line spacing to get our corners back where they should be, and found that our rounds and level flight were all the smoother for it.