That's perfectly reasonable. Just say the bed is for sale, but not available for pick up until whatever date. You may want to set it two days before you leave to give them an extra day in case of emergency, bad weather, etc. You've got the air mattress, so you could do a night on that if necessary.
I'm kinda doing some decluttering before getting ready to take pictures of the bed for posting. My room is a disaster area! Jen mentioned there wasn't any reason I couldn't start putting boxes in the van - stuff I'm not going to mail. So...I'm starting to set those to one side to carry down in a bit.
And I still haven't made the darn phone call. Now I really should wait until after lunch time.
Already had three folks contact me with questions about the desk, so there's that.