You can use your 2017 points in 2016, they would just be borrowed back when you make your October 2016 ressie. That process is pretty seamless. And yes, you can rent the extra points you need. Keep in mind, if the rented points are also for the October 2016 ressie, you need to rent points who's Use Year includes October 2016....so if you are renting calendar year points, you need to rent 2016 points. That said, some pure Trust point owners have non calendar Use Year points, so if you are renting from one of those, you just have to make sure the Use Year covers October 2016.To rent points, just find somebody in the Classifieds section that is looking to rent 2016 points and reach out to them via email or PM.
I do this all the time. I tend to use my points from the next year for the current year. This way I'm always ahead in that I don't have to worry about banking points and if I happen to get hit by a bus, I've maximized my points usage before my demise. 😛So right now, for my 2017 trips, I will be using my points from 2018. For my trips in 2016, I already booked them using my points from 2017.