Legs up/ Legs down?

Go for it. I would make sure your level for the fridge if you have an rv fridge.

You can drop them and stabilize the unit more effectively or leave them up for time and convenience (especially if they are not hydraulic or power driven). Don't drive off with them down. I know it seems unlikely, but I bet it happens to some people!

I've done it both ways, mostly depends on how level the site is, and how much movement in the trailer bothers you.