Sounds like an interesting project, and a great RV btw.
What I actually ment was, isn’t it possible to remove some “other” stuff to get in that area? Eg. to get to the backside of the shower, can’t you just temporarily move the refrigerator? Something like that.
And something like this couls come in handy as well:
They’re much cheaper, if you get them on Ali or ebay or on craigslist. A friend of mine got one for $10 from a UPS facility. Whatever they are doing with these
You see, I can right now mostly only offer some motivational speech, this is some challenging stuff.
But I can give a recommendation for buttons, if you really don’t want to use motion sensors: don’t use the IKEA ones, the are notoriously unreliable. Search for the threads here, the three button remote burns the batteries through in weeks for many people, and the button remotes don’t even start to work.
I’d look for Shelly buttons. They are a nice design, and use rechargables that last like forever. Mine are now running for one and a half years without one single recharge. That is mostly because they fall into deep sleep after some seconds, and are only reactivated by a push. And they can be charged via USB.
The more I think it through, the more I’m leaning towards bridging the 12v connection at the switch, and putting a smart relay behind the light itself. Installation would be very simple, but more importantly it would easily be reversible if I put the right connections onto the relay and used a jumper wire at the switch.
That shelly button is a nice design, but it’s also WiFi. And while there’s tons of options out there for 12v WiFi relays, including the Sonoff SV, Shelly 1, and a few others I’ve come across, the only way to make the button control the switch is through an automation on the hub which does introduce some lag. At least with Zigbee I could setup binding and bypass the hub completely making it as fast as the current switches.
So the search is on for Zigbee 12v relays. And these seem to be a rarity.
From there it would be picking a button. I know exactly what you mean by the Ikea on/off button. They’re terrible. I only mentioned it because I have one sitting on my desk for the Fyrtur blinds. They spend more time dropped off the network than they do actually working.
Aqara has a nice looking button, but I’d worry about the compatibility of the aqara button playing nice with an unbranded switch since aqara is notorious for dropping off the network as well when routing through certain devices.
You’ve hopefully completed your project by now, but I thought I’d share some info here anyway. I’m using Zooz zen31 rgbw relays for my lights. They are 12 volts and with 4 channels for rgbw I can control and dim 4 different light circuits. I’m using Zooz zen34 remotes as switches. They have scene control for loads of extra features like double click all-on/all-off And automations like 1% light in bathroom at night. Those led puck lights are really bright at night and use significantly less energy at 50% brightness. This has completely changed the lighting atmosphere in the trailer.
I don’t have the switches directly connected to the relays via zwave. I did play around with that but it didn’t work well. My home assistant in my trailer never goes down though so this has never been an issue.
My project actually got put on hold last year. This is really interesting. I was just down there this morning opening everything up.
How did you handle the wiring of the relays? From what I’ve been able to gather, at the switches themselves there’s only power and no ground. So did you have to run additional wires for ground or did you install them up at the light fixture itself? Did you then have to run wires back to the rgbw relay since it’s controlling 4 at once?
The remote switches are absolutely genius! At that point it would be very easy to just remove the factory switch completely and place one of these over the little hole left behind. It also gives more of a “home” feeling to the lights when manually controlled.
My travel trailer doesn’t have any switches which is why my project got started in the first place. I have a push button on each puck light on the ceiling. There is no way my kids could reach. I placed the relays in the ceiling at a light and fished wires to nearby lights to have all relays in use. You could run your switch wire into the relay switch input. Ideally they would be momentary switches though.
I did spend some time planning and pulling all speakers and lights out of my ceiling to figure out where I could fish wires. I have zwave in my house so I was aware of some of the devices and the low power usage. Camper trailers are built stupid.
What yaml code (library, custom component) do you use in your setup with these HKW22 hall sensors. I build HA for RV and these could be better than shunt.
I have realised it in ESPHOME. The voltages of the Hall sensor are recorded by an ESP32 and converted into current. This achieves a resolution / accuracy of better than 1% without a shunt resistor. However, I would no longer recommend it due to the complex calibration process. There is a shunt from VICTRON that can be read out via BT and is very common in the community.
I have written NMEA integrations and boat tracking integrations to make HA suitable to be used on a boat as its central system. I have documented all via videos.
and I have a playlist on 26 videos on HA marine projects.
Many can be used in a RV
Something like that.
Whatever they are doing with these 
