Yes, get everything you want to keep out BEFORE advertising it for sale!
Just imagine that somebody drove up, said "OK, I want it, I'm in a hurry, here's the cash, give me the title and a Bill Of Sale, take your license plates, (that's what we do in Montana) I need to get going!" when you say "I need 15 minutes to get our stuff out." He says "I don't have time to wait, if I can't take it now, the deal is off!"
there aren't many people that are in that much of a hurry, but it does happen.
Good luck with your sale.