So my 7 year old has been pestering me for a bow of his own, and I have a nice piece of white oak with good, straight grain. I'd like to make him a recurve, very light of course, between 15 and 18 pounds is all he can handle. The problem is the oak isn't very long, I'll only get 40 inches out of it. Do you think that's too short, or is it doable?