People do that here where I work at the waterfalls. They do alright with it. They have diving gear too.
Looks like you figured out how you need it setup. Maybe a little refining could be done for the strapping. Something like this stuff could be useful. I was thinking a 1-2 setup, clip then pull tight. Quick search on amazon found some bits that could go well. Smart rigging with paracord is another good option. I use screws and washer sandwiching a good not against the wood to secure stuff. I have a Ego chainsaw, pole saw attachment, and power head hanging from my plywood and 2x4 bed rack platform on my work Comanche. Works real well.
Anyway here is some interesting things from amazon for ya. Cheap too lol. Paracord is cheaper though get a 500ft roll for $40 and secure everything, every where lol.
Pardon my messes life is a poor man's project in my part of the jungle but here is how my tools hang. It's all just loops anchored by screws and tension to other loops and screws. Only takes a second to release.