With regard to the fuselage cutout holes, I leave them open. I have not had any issue with fuel getting into that area. With regard to the plug-in stabs, I also use #4 sheet metal screws that are tapped into the stab tube. Shown are some pictures of my current Brio in this regard. Plus a picture of the tailwheel assembly. I used 1/32 in ply as a re-inforcement for the tailwheel bracket, if you can see this in the picture.