Thanks ampsucker. I smelled something (and it wasn't the propane either). They pulled this on me last fall.. ended up costing me over $400 to fill the tank and have it delivered (plus pigtail copper & regulator outside and hookup). I had just bought the tank at Lowes for $119 and drove it over to the place for a fill and got slapped with that spiel.
In a way it probably worked out for the best because I was attempting to get the brand new (yet never used for 3 years) fireplace in our home to operate for the first time and had the old dude sold me the gas and let me take it home myself I would have found (or dangerously not found) that the burner appliance in the house had a leak. I could have blown my house to kingdom come. Instead, by coming home with the gas he charged for the hookup, charged the delivery and found that the burner appliance had a leak somewhere and offered to look at it at the shop and see if he could service it and find the leak (above and beyond what he was there to do). The contractor that built the fireplace used iron pipes without a flexible coupling for the whole rig, so the only way to remove the burner was tediously cutting the pipe with a hacksaw in the tiny space I had to work with. I got it out and brought it to the guy. The guy found the leak in the burner appliance, fixed it and was back out the next weekend to hook it all together and test for leaks.
So I am only faced with how to get a refill for my 100# tank without incurring a $50 delivery charge. The gas lasted all last winter and I used it quite generously, but have no idea how much fuel is left before it is empty. My neighbor is very interested in putting his welding skills to use, so we may end up building a brace\cage\mount for my truck anyhow. I'll check with other local propane fillers and see if they require this mount anyhow.