I think it is possible, the wing has something like a dummy belly pan made of balsa wood. You glue that thing to the wing in order to give a mid-wing location impression. However, you can put some fuel proof to the inner side and cut in accordingly. Then you can screw to the wing a ring with a special nut for tuned pipe and place the belly pan over it with screws. If I were you I would put 4 little pieces of hardwood with blind nuts in order to hold the belly, do not use just wood screws on the hard wood as they will become loose with vibration.

Good luck, if you want some more info on the plane construction etc. you can download the manual from Kyosho web site.

Rgrds,

Nick