Easy to do, get from your hobby shop some light fiber cloth and lay it over the belly with slow cure epoxy or even water base resin will do. I suggest fit under each wing little ply fin/skid to protect your linkages and avoid possibility of wing tip digging into the ground on landing. I have done hundreds of flights with similar size 64mm "F-16" model by Kyosho back in the old days of brushed motors, bungee launching them , much safer than hand launch, unless you really know what you are doing.