It's rather stunning how heavy of balsa is used in some kits and ARF's. I had one kit of a Stik that had 18 lb density wood, not the kind of stuff I would normally use with a triple beam balance gram scale. Six to eight lb wood is what I try to use for most construction. The stik will likely need the bathroom scale with the 18 lb stock, wood that the Navy rejected for rafts.

I usually put lead into the rear crankcase cover if I am tail heavy (rare).