You should be able to increase the air pressure in your permeate tank. You need to be at the bottom end of where your pump output pressure decays to or the same pressure where it starts at. Need to use a good gage to check it with. If you are running an RO in the camper you really need to keep it pressured up all the time unless you have a new style that shuts off when the permeate tank reaches system calibrated pressure. We use a GE Merlin system which is larger than you need unless you want to run all the water through it. Any of the units at the big box stores should work fine if properly installed. We like the RO permeate for ice and drinking. Be sure you change out the carbon filters each season at a minimum though.