I have an air compressor in the garage, always on. It’s about 150 feet from the railroad. I put the regulator there, and then ran the thin 1/8" line to the back yard. I made an “accumulator” from 12" of 3" ABS pipe, so it feeds the switches, and then is refilled by the main line. Works great.
You can buy a small air tank from the auto supply houses, fill to 125 psi, and run all day, as an alternative.
I run just the air line to the switch, I use the digitrax DCC decoders to run 4 switches. I can mount these wherever it is convenient, out of the elements. They are powered from the track, so put them in trackside shantys, etc.
Regards, Greg