Craig, I agree with your idea of a skills test. I have talked with many people for years about this very idea. Here is one major drawback to it. I know many hunters, and you probably do also, that the skill is not what causes them to make less than perfect shots. It is that they have no self restraint. They cannot allow themselves to let a animal walk, when only a marginal shot is offered. I do think that this can be helped, it is just not as easy as a skills test. You have hit on a good idea though!
What I do, respectfully disagree with you on, is this, I do not feel that crossbows should be the vehicle used to introduce younger/more hunters into archery season. If someone without a disability wants to hunt more, they should use a conventional bow, like the vast majority of hunters supports, not just myself and a few others on this thread who disagree with crossbows.