4 way camera wiring. Help Needed.

Hello all, I’m starting the process of upgrading my sort of kludged redneck pickup into a more functional work and adventure build. I’ll make another post later for a more extensive electrical overhaul, but for now the pressing concern is cameras.

For a few years now I’ve had a Pioneer AVH310EX head unit with a cheapo backup camera from Amazon. It worked great until I lost part of my exhaust and the wiring got melted. So I want to take this opportunity to upgrade a bit.

I want to add cameras in the front and wing mirrors and be able to switch them on at any time. I’ve seen some switch boxes for the 4 way, and some camera options, I feel pretty good about that.

Where I’m stuck is visualizing the wiring so I can have the selectable cameras as well as the automatic reverse cam. Just don’t want to cross anything up and cause a short. How would you go about this?

Bonus questions: I would like to be able to easily unplug the rear camera and connect a trailer camera. What are my options here?

What wiring and fuse do I need for a 750W inverter mounted in the bed/toolbox?