Probably need to look for less than a short. Water is conductive but not THAT conductive.

Can’t speak for mechanical keyboards specifically, but finding what you want for the cheapest price is most often done best on eBay rather than Amazon.

Look into fixed wireless or 4G/5G home internet. Fixed wireless is sometimes exactly what you need in spots like that. It is not 4G or 5G, sometimes it is just long range WiFi or other lax spectrum.