I think it depends on where you are able to get for your rentals. We live by Glacier Canyon in the Wisconsin Dells and see rentals for it quite frequently on Craigslist and EBay. They are going for about twice maintenance fees or about $10/k not counting any VIP discounts. Generally the Guest cert is included so you would have to factor the 99$ guest certificate fee.
I believe the 2 main reasons for the profit margin at this particular resort is 1) they are advertising on mediums that don't only attract timeshare owners who already have an idea of costs associated with them. People on redweek and wyndham sites know what the MF are and aren't willing to pay that price when someone else is selling points for at or below cost. 2) Since this is attached to the Wilderness resort, the resort sets the price point. When we stay there our MF of our points cost about 30-40% of what it would cost if we booked the same room through the resort it self. For example next month we are staying in a 4 bed pres for 4 nights for 106K points. At 5$/K that would put my room cost at $530. If we were to book a 3 bedroom condo (it sleeps the same number) through the Wilderness itself it would cost $1,553. So as you can see I could try and rent my reservation for $1,100 or so still being well under the resort itself and be making double my cost. I think if you are able to get certain weeks it may work out for you but you would have to find highly in demand resorts and plan 10 months out which is quite a while to hold inventory.
Jason