Read reviews for the Uber Bivy by Miles Gear's as submitted by your fellow paddlers. All of the reviews are created and written by paddlers like you, so be sure to submit your own review and be part of the community!
It is compact and light weight. It comes with it's own stuff sack. I use a waterproof bag for it as well. It fits nicely into my kayak. It comes with a ground cloth. And it is available in white - any other color will not be as breathable and waterproof. Thus far, that has not been any problem for me. And the trade-off for some "cool" color is well worth it.
I'm 6-3 and 245 and haven't fit any other bivy sack - the Uber Bivy is like the Taj Mahal. Lots of room, a couple of convenient pockets for glasses, wallet and such. Set up is a snap - two identical, flexible poles slide into the bivy and form a space for your head. A mosquito net or a solid closure allow for a comfortable night either under the stars [and bug free] or snug in your own world. Both work well.
Dave Miles knows what he is about and makes every bivy himself. He only sells on the internet and by word-of-mouth. Just Google - Miles Uber Bivy and/or go to milesgear.com