2017 T-250-MR-148-3.5-ARB AIR-LOCKER REAR
I am using a Latching 6 Channel Relay Board with momentary contact switches. These switches are switching the negative as you describe. No need for load carrying 3/4 way wiring, also as you describe.I'd use a ESP32 and a 8 channel relay board (or maybe a 16) and wire everything off that. I'd mount that beside the new house fusebox. I'd use momentary "normally open" switches to trigger the ESP based upon a "change of state" of the switch. I'd write the code so the ESP32 Inputs triggered by a ground signal. That way every switch would only need one very small wire to it from the ESP because I'd ground each one to the body locally to supply the ground. I could have used as many switches as I wanted to for every single device. If I would have done that, I could have controlled everything from my phone over a WiFi access point on the ESP and even used timers in the code if I chose to. Temperature sensors and photocells could have been implemented as well. Manual switches could have been grouped together and wired using just one cat 5 wire allowing 8 switches to be wired with just one small cat 5 wire. The sky would have been the limit and the costs would have been far less. There would have been no need for 3 way or 4 way switches and all that 14 gauge wire. Better control, centrally located components, less wiring, less voltage drop and less chance for a malfunction! The boards are only a few bucks and the 32's are inexpensive. Hindsight is 20/20 I guess!
Thanks for introducing me to the ESP32.