If you have most of the equipment, why not get a soldering gun instead of using pepto bismol? Seems like a creative solution but I don’t think it will hold up to vibrations or even regular use.

Install it with the mouthpiece facing the wind

Look into the Shelly switches. You connect through wifi and Bluetooth but it’s an open device in terms of how you run it.

It has an esp8226 inside but it’s ul listed and fits inside the switch housing. You won’t have wires running into a socket and it won’t look ‘dangerous’ per say.

You are going to need one of those hot air soldering guns (rework station) I think. You can heat the back with it, it’s the only way I know for the gnd pads if you can’t use a hot plate or oven.