Alan, for the quick fix, sure a switch and inline fuse wired to the isolator (coach battery side) would work. At night you can turn it off, or else everyone is going to fall out of bed.
3-4 minutes is a long time for the compressor to run, which means your bags were low.
There is a small inline check valve that should be installed in all air systems, since most compressors do leak internally.
I placed the check valve between the tank and the airbags, so my bags hardly ever go down, just the pressure in the tank does.
In case you are interested to know why I placed the check valve in that location:
The grey box by the compressor is the pressure regulator. When the pressure drops ~80 psi the diaphram closes points, which sends juice to the compressor. Once the pressure reaches ~100 psi, the points open and circuit is cut to the compressor. Sounds like a nice and easy automated system, except without the check valve the airbags also deflate to 80 psi. So until you reach the 'cut-in' psi of 80, you are actually running your bags to low and the compressor has to work harder to get everyone back up to 100psi.
I would never have figured the above out, if I would not have installed an inline pressure gauge.
Disclaimer: the above applies to my system, other system may have different leveling valves that may prevent back leaking of the airbags.