What more do I need/need to do?

[Eden]

I use these drybags for kayak camping:
http://www.sonomaoutfitters.com/ista...id=PDS1633!249

There's a bunch of different sizes, you stuff your stuff in, fold down the top, and then undo the vent at the bottom to squeeze out all the air.

They work pretty well & are waterproof.

(I have no idea how they compare to spacebags)

I've been using some less fancy ones for commuting (Sea to Summit bags) as I bring my camera back and forth to work with me and absolutely do not want it getting wet. They've held up very nicely for 2 years now. I picked these ones because they are light compared to most dry bags and less expensive.