RE: KIWI PATTERN PLANE
Rafa -
I increased the rudder about 50% on mine because of the heavier motor and I wanted to make sure it snapped quickly and could knife edge. I used either a 11 x 7 or 11 X 7.5 depending on the nitro I had. You could adjust the length of the retract gear legs so I just made mine long enough for prop clearance. I think I used 2 " thin wheels.
I remember now - the foam wing as a tail dragger and the stock wing (see pic with skis) used the supplied main gear. I could "plug in" the nose gear if I wanted a non-retractible trike. When the retract gear was used, I used a short piece of 5/32 wire in the nose gear bearings.