I guess if it were me I would get my son to 3d print a suitable plastic part to fix an available connector in place. It is surprising how often this is a real solution to those kind of problems.
I used to have the male half of one of these jury-rigged (bit of metal bent up with some self tappers to fix the connector on to the front bumper) on to the front of an old car I used to commute in.
I left a small blower heater in the car wired to the plug and then on cold nights I'd plug the female end into it, with a 3 pin plug on the other end.
I had a timer which would switch this on half hour before I left for work. It'd de-mist the car, heat up the inside and melt any ice on the screens. It worked really well. Plus I felt pretty smug on the days i remembered to connect it up.
Why am I telling you this? Well after about 6 months, a combination of road salt and rain/water corroded the pins pretty badly. It still worked, but I had to periodically clean it up a bit.
Later, when I did a similar mod on another car, I simply bought a spare female connector which I put on a short string, and plugged that in when I wasn't using mains power. That made the situation better, and kept the pins dry.
You might want to consider something similar….. if you do something similar. I.e the connectors are only waterproof in pairs.
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