I agree with the suggestion that you buy one of Doug's pocket survival packs and add to it.

the knife you attach to your PFD
heatsheet
Couple of zip-lock baggies or Gerber bags (search) to carry water in.
4-6 MP1 tablets

AND- I'd re-think "deployment". It isn't hard to be separated from your boat and the gear you stow in the dry bag. Doug's kit, even with a heatsheet, can be attached to your PFD (or some PFD's have a secure pocket. Somehow, on your person. Consider http://www.aquapac.net/usstore/mini-whanganui-br-644-1894-0.html