Originally Posted by bkbroiler00
maybe i can find one used and in good shape.
....good luck with that!! In my experience, you can probably find a used RV style tank that will require cutting a hole in the van's rocker panel for access (I think Sportsmobile sells the access door to cover the hole); it seems that used "van" style tanks are rarer than hen's teeth.
One other thing to consider is that the newer tanks have additional (mandatory) safety features like overfill protection, etc. If the used tank that you find is too old, you may struggle to find places to fill it.
One more consideration is doing the plumbing...rubber line or copper, etc.
I'm not versed in the details of tank safety.....but other members here may be.