Advice for living in a trailer for the summer?

I just got an unpaid summer internship in an extremely expensive beach-type area, and needed a place to live for the two months it lasts. After asking just about everyone I knew, through the grapevine I found a place to live, in a trailer in someone’s backyard. I get to live for free there in exchange for working for them part time.

I’ve practically never even set foot in a trailer. What’s it like to live one in the summer? Is there anything I should know? Anything I should bring? Any advice/experience is appreciated!
edit: it’s a pop-up trailer, whatever that means?