I agree with the Bayou Bengal. Renting points is a little safer than just getting something through e-bay or something because you will have a little more information about them than just an e-mail address that can be dropped or changed. Because they are booking the rooms for you, you will know their name and their home address, you could probably ask for their phone # as well because you may be discussing the details. If you sign and fax to each other a fairly simple rental agreement then you should be able to bring it to small claims court if they canceled the reservation after you paid it or something. I think that there are some simple agreements like that floating around on here.
I would think it is a good idea for both parties to pay some portion of the cost right up front - maybe something like 1/3, and then pay the remainder before 30 days out. That way there is some protection for both parties. But of course that would be for the renter and rentee to agree upon. If I was renting, I would ask the renter to check the dates I wanted, if they were available, I'd ask them to book them, and fax me the letter they get from member services, then I'd pay them the remainder before 30 days out so that they are safe (after 30 days it is tougher for the renter to use the points and they can loose them if the person cancels).
Don't expect to be able to call member services and check the reservation. They may let some folks fall through the cracks on that, but technically I don't think you should be able to do it.
It should be pretty painless and easy. Like the LSU Tiger said above, look for someone who has been around a while.
You are going to do a lot better on weekday costs, I'm not sure if it would be worth it to rent points for a weekend stay. Unless you really need a 2 or 3 bedroom, you should check mousesavers.com and play around with comparing things.
DR