I'm going to run a bit counter to Paul's suggestion about air speed and say that you need to just keep the Reynolds number out of the lower end where the problems occur. Paul suggested speed as one way to do that and that is certainly valid. however wing chord is another way. Shorter aspect ratios that ensure the wing chord is a bit wider will produce a higher Reynolds number for any given airspeed.

So how wide do you go? Funny, this is a major topic in the RC sailplane world as well. Basically higher aspect ratios produce less induced drag and limit the tip vortex losses. However they force the wing to operate at lower Rn's and thus "eat away" the supposed performace gains from the high aspect ratio. The glider guys found that there is a "best" case where the Rn and the AR is balanced much like the best L/D of any wing. For models in the 100 inch range I believe the optimum aspect ratio is about 8:1 to 10:1. Open class likes to run 10:1 to 12:1 or even a bit higher. 2 meter is actually best at 6:1 to 8:1.

Also RELATIVELY higher speeds and SAE flying are not mutually exclusive. Use something like FoilSim to find out what your speeds are for various weights and Cl's and do the math to determine the Rn's. I suspect that with full loads the required airspeeds will be high enough that you don't really need to worry about the bad charactaristics of the bottom end of the range. But having said that you can find tune the flying by letting the model climb at a shallower angle as long as it meets the performance tasks. That will tend to keep the airspeed in the higher end of the model's range. Which is ALWAYS a good thing with a model loaded as these are. I don't think I'm making up stories is I suggest that most of the crashes of these types of models are due to the pilots getting greedy with the up elevator at the wrong times.