I'm totally new to this, only googled it after reading your first post... but looks interesting. How would the control panels look exactly? Based on your description of running cat5 to each panel, I'm guessing you'd be using a
PoE ESP32 board like this one and then somehow wire your momentary switches to that PoE board? (I haven't gotten far enough to figure out how to wire the switches).
And then the cat5 cables would be routed to a networking switch with another ESP32 board connected to
a relay board like this one?
Sorry - total noob here. But you've piqued my interest!
No PoE needed.
No network needed.
NOTE: Be careful, some relay boards require a 5 volt signal. ESP's do 3.3 volts so they will not trigger a board the needs a 5 volt signal. There's ways around that but just get the right board to start with or use a Arduino. They do 5 volts. Personally I like ESP's
I'd keet it simple. All I would be doing is triggering the ESP inputs by sending a ground signal by pressing the switch. Each "new" ground signal would trigger a change of state of the relay.
I'd just use cat 5 as regular wire. I have a 1000 foot roll here. Cat "anything" would work as long as the wires are color coded. The real advantage is that you get 8 wires in one run and since the volts / amps are so small, the small gauge cat wire would be perfect. I'd just strip and solder to the switches. There's 8 wires in a cat 5 so each switch would get one wire and they'd all be connected together to one ground (to the body). A blank cover plate or some thin wood with holes drilled would work for a mounting plate.
I'd use simple normally open switches like these:
Color coding like that might be nice to keep from having to label the panels. You'd quickly learn what each color did. I don't see ever needing more than 8 switches but who knows.
Personally, I'd limit it to just my 12 volt stuff since I only have to control the inverter on or off. That would keep the A/C current away from any 12 volt stuff. I would just switch the 12 volts to the inverter with the ESP and one of the relays.
One switch could turn on or off multiple relays. You'd just write it into the code.
For instance:
Blue switch controls "front lights'
Green switch controls "rear lights"
Black switch controls "both front and rear together".
Red switch turns all the lights off and turns on the TV.
Yellow turns the outside lights off after 5 minutes
Whatever you wanted it to do. If you haven't played with Arduino and micro controllers, there would be a learning curve

.
You have to start small with blink. I remember when my first LED blinked. WOW I was excited LOL!
Download Arduino and get a ESP8266 to play with. YouTube is your friend.