add an extra knife. Some thing that will cut webbing under tension. I have had the cut a main prussick once pulling a bucket boat off a rock, there was no way to release the system with out destroying the raft, instead I just dissembled everything except the main pulley and prusick, uncoiled the rope, cut the prusick and let the rope through the system. Not ideal, but its crazy what crashing water will do to a even a small kayak.
If you are in a kayak, I would get extra prussicks instead of assenders, add a 20ft section of 1/2 webbing aka super tape. often 6 and 10 foot sections of webbing are not enough to tie off rocks, last time I unpinned a boat all we had to tie off was a boulder size of a van.
a unpin kit is useless unless you know how to use it. I have seen people with them that dont even know how to use them, make a possible rope hazard in the river. Practise a basic Z-drag, learn to tie a water knot, bowlin, figure 8, clove hitch, in the dark. If you can master those 3 knots, and 1 hitch, and the z drag you will be able to make 7:1, releasable systems, etc...
I recommend "Self Rescue" its a falcon guide, it is specifically for climbers, mostly aid climbers, but the information is invaluable. Covers everything from pulley systems to multi rope carriage systems. Or go find a aid climber friend, buy him a King Cobra and have him show ya some tricks, you can tell who's a climber when the unpin kit comes out....