If a pressurized water source is unavailable, the tank can be filled and then pressurized by using a standard bicycle pump.
If it can be pressurized with a bike pump it can be with a air compressor . The issue would be over pressurizing the tank. As for filling it from a jerry can, a simple hose set up can be easily put together.
That's the direction I was headed. I was looking to make a tank out of 10" or 8"" diameter PVC pipe with end caps.