Install a transmission cooler between the air compressor and the hand pump inlet. You could have the cooler lay flat and put a block of dry ice on top of it.
Or, you could submerge the cooler in a container of ice water.
Even just having a good fan or window unit air conditioner blowing across the cooler would give a much cooler air charge to the pump and prolong the pump cycle prior to pump overheating.
You could also install water traps at the compressor outlet, and at the pump inlet to remove as much moisture as possible.