On a taildragger the centerline for the mains needs to be even with the leading edge of the wing on most models (typically 2-3" forward of the CG). Yea, you need some plywood under the mains and the trianglular stock inside, but I always use some real thin fiberglass tape/cloth on the outside, ~3/4" fore and aft of the plywood plate and ~1" up on each side, and thin CA it in place, lightly sanding with 220gr when dry...that is where the most stress is...tearing out. I use that method of reinforcement on high-stress areas of a plane for light, strong assemblies. OK, there is a slight ridge in the covering...so what!...come a little closer so I can kick your backside for whining about it!

I rigged a tailwheel on a LT-40 that works great. I ran a second pushrod from the servo to the opposite of the rudder servo control horn side to the bottom of the plane. I had to rig a tailwheel bracket with a control horn...you can do it, it's easy...I think I used a Dubro bracket to start with. The result is a superb ground handling plane.