Is it cheaper and/or easier to live in a boat or a van?

I'm interested driving a semi-truck for a living and I know that over the road truck drivers practically live in their trucks and seldom stay any other place, so I know living in a vehicle can be done. I'm looking into cheap places to live, also for some reason it is easy for me to finance a vehicle, but I can not get a house mortgage due to bad credit, and I don't want to waste money on rent, so I've heard of people living in boats more often than vans, with that being said, is there a reason why?-are boats cheaper, more convenient, is it a "legal thing" or are there more places that boats can park(dock)?-etc.

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