I think he was questioning what to do without ailerons as I mentioned that was an access to the wing without cutting covering. Lacking those, I'm afraid it's slice and fasten from the underside . . . unfortunately. It would be impractical to try and add enough weight inside the fuselage, though I try to offset the battery to the opposite side of the muffler where possible when the engine is installed with the muffler to one side.

Fishing sinkers make great weights as there is a hole or loop for a mechanical attachment (and epoxy or otherwise cement it, too).