Say what you will about it sounds like a pretty good testament for JB Weld.
I don't know of any legal issues anyone would have with curtting the frame. A lot of people do it, and actually when they are finished it is usually stronger than before due to the extra reinforcement they weld to it.
I do thing the way you are going is a better way. Why cut one when you can find a short frame to start with.
Keep us posted!!