You could use your present points to book the start of the vacation, and line up a rental from someone like David's to book the last few days of the vacation. What you're describing is a transfer. It would be tough to line up a transfer for your resort and UY to make it work seamlessly. You'd have to do this every 3 years, and I just don't see either of these two scenarios as being workable.
I assume you are looking at a 6 night stay, since 6 nights at a 2 bedroom value in adventure season is 155 points. This would require 5 OTU points. If you extended it to 7 nights, you'd need 35 points. But, since you're limited to 24 OTU points, you couldn't do that.
The smallest DVC contract is 25 points. If you bought a 25 point contract, you'd have a total of 225 points every 3 years. That would be enough to book a 2 bedroom value in Adventure, Choice, and Dream seasons without any need to use OTU points.
However, you won't be finding a lot of 25 point contracts coming up for sale resale. Those that do will be fairly close in price to buying the same points direct, due to the higher closing costs. And, you'll be waiting potentially a long time to get a 25 point contract that matches your resort and UY. For a small contract like this, it's often better to just bite the bullet and buy it direct.