Re: Thinking about maybe picking this up good or bad idea?
It's a good idea if it works for you. The tank in the picture looks as good as new. There are pluses and minuses with either choice. Be sure that the tank is set up for vapor withdrawal if you are going to run a heater. The last photo in the pickup does not show any hoses at the top, the pickup may have been set to burn liquid. A genny can be set up to burn liquid or to burn vapor, depending on the carb. Most burn vapor.
If you use a fixed tank, you will have to drive to the fill station, unless you have the tanker coming to your house and ask them to top off the bus while they are there. Many people prefer to use the 20 lb/4 gallon BBQ bottles, because they can toss them into a dingy or beg a ride into town to get them filled without moving the bus.
You can even do a swap at a big box store in an emergency, but know you will get the exchange tanks only 3/4 full, that's how they make their money. It is much cheaper to have your tanks refilled.
The advantage to the fixed tank when running the genny on vapor is that there is more liquid surface area in a horizontal tank. This allows the vapor to rapidly boil off of the liquid under a heavy load. For fixed generators in places we can't get a tanker to drive to, we usually use a manifold of at least three 100 lb/22 gallon bottles for an 8 kW genny, and 5 bottles for a 12 kW genny. Before I became educated about propane, I thought it was just for added run time, I didn't know about the surface area factor. 100 lb and 20 lb tanks have about the same diameter and surface area, unless you cheat and tilt a tall tank.
Lacking further information, figure the 48 gallon tank rating is specified as "water gallons," so the 80% propane fill might be about 38 gallons. If you are lucky, it will actually be a 60 water gallon tank that takes 48 gallons of propane.
We use about a gallon per hour on a 12 kw genny lightly loaded. You should be able to figure your run time from your genny specs to help you decide if the tank is big enough.
Someone said "Making good decisions comes from experience, experience comes from bad decisions." I say there are three kinds of people: those who learn from their mistakes, those who learn from the mistakes of others, and those who never learn.