You can mount your poles to crosses, and still turn them around to get lower or higher, depending on the length of the crosses. A little less than knee high would be as high as you'd want to go and still have him just walk it. Higher than that is probably too much. He'd likely want to jump it.
Well that makes more sense, that would make it more of a work out.
Learn something new everyday.
I guess I'll show this picture to my son, and see if he can knock me some "x's" together before he leaves today. I think we have some lumber out there he could do it with.
I may go out there myself, since it is raining, nothing else much to do, Surely I could do that.
Becky