I usually cut out a 1/4" thick plywood piece that will fit in the floor of the fuse right ahead of the former that holds the front of the wing and the next former if there is one. Then glue some triangle stock on the sides of the ply piece to take the vertical load. That will put the gear in the right spot just ahead of the leading edge Doesn't take a whole lot to hold the gear. Look at what they used where the tricycle gear mounted. (One little piece with a groove in it.) If you are using new gear, attach it with sheet metal screws that will pull out in a hard landing. Saves the belly of the plane. I wouldn't recommend using the wire gear that comes with ARF trainers. Too soft most of the time. There is a good fiberglass gear that springs back. Tetherite or someone makes it. Add a pushrod for the tailwheel or try a freewheeling tailwheel. High rate rudder should let it steer enough to taxi. Then go to low rates for takeoff. I am using a two-piece swept back set out of my junk box on my next one. Probably be tippy but that's OK. For some reason I bought a trainer the other day after flying nothing but 33% gassers for a while. It will be converted as I assemble it.