Oba
I use a 90 cf scuba tank, found it in a pawn shop real cheap when I first started setting up my Ranger for off roading but if I had to do it again I would use a on-board tank and compressor system.
The scuba tank works fine, easy to remove but I have to take it to Carson City for refills (3 to 4 times a year) with my Suburban cuz the one hour round trip on the highway would be too much ware and tear on my Baja Claws.
Refills are $5.35 and there's a Hydro test once a year.