Why not just purchase the USH youth model? It weighs less than the USH (the barrel is 22 inches long instead of 24 inches for the standard models) so it's not too heavy to lug around, but weighs more than the lightweight model so you don't get the snot kicked out of you?
The length of pull is a bit shorter, but most people are wearing heavy clothes during the gun seasons. If it's still too short, you could always add a slip on limbsaver pad (over the existing stock/pad) or purchase an adult stock.