btw, i should add, I used FOUR fuses for that power panel above, 15A for the USB, 15A for the cigar plug, and 30A each for the 2 powerpoles. thats *ridiculous overkill* ... but I could see scenarios where would be pulling nearly 30A from a powerpole. the dual USB won't ever draw more than 2-3 amps, and easily could have been wired across the same circuit as the 15A cigar plug, but I used a seperate fuse in case somehow the cigar fuse was blown, I'd still have USB charging. did I mention I'm a retired engineer?
anyways, those marine style plates are readily available in all sorts of combinations of 1, 2, 3 plugs, where each hole can be filled with a volt meter, a cigar socket, a usb charger, etc. I actually started with one that had 2 cigars + USB< but changed one of the cigars for the dual powerpole. if you're mounting it on the typical thin plywood used on camper interiors (or thin fiberglass), I'd suggest using a backing plate of 1/4" 'hobby' hardwood plywood. each of the round plugs needs a 1-1/8" hole, I used a
I bought off amazon...
first, I drilled a single screw sized hole for one of the corner mount screws, and a similar hole in the backing plate, then lined up a corner hole of the face plate, that hole, and the backing piece, and temporarily put a screw+nut together to hold them all in place, then drilled the other 4 corner holes rigth through the holes in the faceplate, while holding the backing plate tight, and installed the other 3 screws+nuts. I then used the face plate as a guide for the 1-1/8" hole saw, again holding the backing plate tight while I drilled each hole right thorugh the camper thin ply + the backing plate. I took it all apart again, and use da bit of medium-coarse sandpaper to dress the edges of everything, then assembled the faceplate + backing plate + 3 sockets...
I dunno if it I would have done better if I'd tried to measure and mark it all up and do it by the ruler, but when I was done, I realized, the whole thing wasn't quite perfectly level, hah hah. close enough for jazz.