What do you mean by stability?
- lateral stability (falling by rolling to the side) ==> you need more width (especially at nose and tail), not necessarily volume.
- longitudinal stability (falling forward or backwards, having a hard time getting up because the tail sinks) ==> you need more volume, and probably more length.
I agree with jviesinga, the simplest solution could be the hipster 8'10".
And also, look at these tips, it is very important to keep your feet away from the rails:
www.seabreeze.com.au/forums/Stand-Up-Paddle/SUP/Mastering-lateral-balance-on-a-small-SUP-board