If my metric conversion is correct, your 3.5 ccm MVVS's work out to about 0.21 cu in, or roughly a pair of .25's.

Hobby Hangar offers kit/ARF versions of Rich Uravich's ~50in OV-10 Bronco. Twin booms and rudders, and it's a pretty stable flyer. Might be a bit underpowered if your MVVS's are only .20 cu in., so you'd have to build it light.

Another choice would be the Hobbico Twinstar... only a single rudder, but supposed to fly OK on a pair of .25's