My standard .15 RC "hotrod" was [is] to take an unused 1/2A C/L foamie wing with about 32-34" of span and mount it on the smallest balsa fuselage I could come up with. At less than 28 ozs, a OS .15 will haul your plane like it's a .155 Howitzer round.
Not so good for combat, but lots of fun.