Well, I wouldnt take as gospel-just 2 guys shootin the chit but. I stopped by the RV shop. Wish you had someone local as knowledgeable and willing to share what they know. Quite of lot of information-I explained circumstances and asked questions from as many prospectives I could think of. Bottom line though, pretty much what others have outlined.
Basically when OPD became law, older non OPD tanks, regardless of configuration could not be refilled. Because of valve/tank internal plumbing, older horizontal tanks couldnt be retro fitted, specifically horizontal hard mounted tanks. Needless to say this required folks to replace tanks to comply-and at rather a large expense. Enough of a clamor was made that the law was changed approx. a year later.
Fixed mount horizontal tanks were made exempt from the OPD valve requirement though they still need to follow recertification guidelines. This was the initial source of confusion when refilling an older OPD exempt tanks (and still is).
Newer OPD horizontal DOT approved tanks must be refilled in vertical position. Kinda stuck there. He was unaware if there are any specialty tanks that might conform. ASME tanks which might work being different, are expensive & heavy can be filled horizontal. Practicality of mounting ASME in a TC not simple as far a retro fitting.
He couldnt really make a suggestion, other than trying to find re-certifiable older non OPD tanks. He did mention even if, refilling on a TC would be problematic at best. Either due to interpretation of OPD requirements, physical location and or restraints. (hes got assorted fittings allowing to fill 'almost' anything but still they are pretty good size)
He also mentioned, refilling a tank on a TC due to the confines is not something he would do if he had a choice. I didnt pursue why. Nor did I asked about current MH etc.
We did briefly talk about frame mounted to truck. Extensive as far as body mods. Something I might seriously look at if I needed to change stuff but might be prohibitive cost wise and quantity might be limited. Learned a lot but only relaying what I found, even though it doesnt help.
