It's only been a week, but what are my options if they do not return and the RV just sits in the slot? 

In this case, he gave us ample notice to (most likely) fill that slot, however, I'd like to protect us in the future.

Its surging slot so if you time it right on the buy in (around 10800ish) and the sell (I believe in the next few days it'll steady out at 11300 based on trends last few weeks) it's not too far fetched to net 1000ish as you use the surges to your advantage.

I assure you there are sharks looking for chum; and YES, vet those sponsors. 

Hell when you pull back the curtain most people would be shocked to realize that all those prim and proper super nice 50 year old lady Realtors that seem so nice; those ladies are some of the most cut throat sharks in the game.

Most seem to want a showing (i am currently making a quick google sheet with available time slots on a Sat morning for my dad to show).

I actually had a Financial math class in HS and we watched shark tank for 2-3 months.

You are swimming with sharks... 

This young man is 25, if he plays his cards right and scales slow, by the time he is 40 he will be a millionaire many times over.You just have to be careful, there are sharks out there that are not scammers per se, but they are just very pitchy and slimy and are allergic to honesty. 

This group of pees will also help you avoid the sharks who just want to pitch you