You can build them any way you like.
I think I'll make a video of taking them off and putting them on. It's really easy, quick, never comes loose, never gets in the way of a load or tangled up with anything. I have to say this is one idea that I like just the way it is. If it's the fabrication of the hold down parts that seems scary, don't worry about it, that's the easiest part to build.
here are a couple more videos...
https://www.youtube.com/watch?v=A-agEjzGp_s
https://www.youtube.com/watch?v=AFGPMRVoUGY