Propane Tanks: Gas Valves Question?

Not sure. I have a 1998 Pastime. The horizontal tanks give easier access to the works than vertical in this application. They are a bit different inside and won't fill as much. But the huge difference in cost is mostly just gouging I think. Some places will fill them in the camper, others want them taken out, some are set up so the hose won't reach outside of a perimeter near the tank anyway. I've replaced one $160, and plan to just replace the other when it is empty. Traveling BC and Alaska I'd just as soon not argue with pump jockeys. Propane tanks also are supposed to be recertified every 10 years, I think, but I've never heard of anyone enforcing that one. I usually only fill up once a year. We do all the cooking outside and only use the propane to run the refrigerator or heat the occassional tank of water.