No plans for body filler, that will wait for the painter to decide. We wound up with a leak in the plastic gauge for the fuel tank after we had filled it with 20 gallons of fuel. It had tested fine with just air. Then we removed the top of the tank and removed the plastic sight gauge, replaced the plastic with a .040 thick plate of alum, properly gooped up with tank sealant, and riveted the plate on the inside. Then we gooped the rivets and the outside of the tank over the holes. Installed a mechanical gauge in the top of the tank and reassembled the tank. Reinstalled the tank and no more leaks from the sight gauge area. We had assembled the tank originally when it was hot and wound up with a leak from the front electric gauge plate when the weather turned cold. We tightened up the mounting screws 1/8th of a turn and no more leaks! The plastic sight gauge cracked when we filled the tank with fuel.