I use an 120 gal Propane tank, I have a draw tube in it, COV and PSI Gauge and it goes to a 4 mic filter, 15' Diesel Hose then to an Auto shut off nozzle, just like the ones at the pumps. I use an air compresser at home or stop at a gas station and pump it up to 30 to 50 psi, fill up my truck anywhere I want to and it shuts off when it is full (click) done. The tank is built for 300 + PSI and the relife valve will pop off the air on top inside if it goes to 250 psi. I put it in the back when I need to drive far far away. Yes it takes up 1/2 of the 8' bed room, I can close my cover on the back and no one knows it is there. I am working on other sizes too. Last summer in NC, FULL under a black cover No PSI build up, I kept 35 psi in it. and I think it was at 85 or 90 that day. It will take a lot more abuse then the 35 gal tank on the under side of my truck. Yes I straped it down with 2" HD 10,000 LBS straps. better then the two 120 gal ALUM tanks on the sides of my 18 wheeler I drive.