A caravan is a mobile home so you could say "We went camping in a caravan last year" or "Dad bought a caravan withthe lottery money we won" or "The camp site was a tent and caravan park only"
Use it's (with the apostrophe) only when you mean "it is" or "it has." For example: It's time to go. (It is time to go.)It's been a long time. (It has been a long time.) Use its (without the...