nice LT 40 BTW. that will work fine, try it upside down with the front string looped under the prop shaft and the back loop to a single point such as a tail wheel bracket or a screw that is dead center as far back as possible, a loop around the fuse in front of the tail will hold it to well and decrease free motion. very nice to see you building a kit, your gonna love that LT 40

it really can't be balanced until it is covered and radio is installed almost ready to fly. always balance with empty tank. you can make a small hole on the bottom of a wing tip and glue a wieght to the inside of the tip rib if needed. stop by your local tire shop for a cheap source of stick on wieghts used on mags or old standard rim wieghts, a good handfull will last years. or if you know any shotgun reloaders hit 'em up for some lead shot. or just stop by a dark parking lot with a pair of plia... oh mayby not