Way too much stuff to have attached to your PFD - consider that almost all PFD's have 16lbs of flotation.  that is because the body is about 90% water, which is neutral buoyancy, so 16 lbs is about all you need to float.   Depending on how much buoyancy you add with your "packaging", you will likely reduce that 16 lbs by a fair amount, and not float as high as you should.  If you actually gain a lot of buoyancy with your ditch kit attached to the pfd, it will have a tendency to push you down face first - no way you would be able to float on your back (which is necessary if you are "swimming" a rapid or); no matter how well you have your kit waterproofed, water is likely to seep in after a while, and that will reduce any buoyancy you have in your packaging.   

Ditch kit s/b for extremely unlikely occurance - keep the total weight to maybe 2 lbs or less that attaches to your pfd.  I have a small fanny pack that I use for my ditch kit - I simply thread the strap through the armholes of the pfd and it hands down near the base of the pfd - small and not in the way.

as for the stuff on your list, I'd back up a single butane lighter with stormproof matches, not another lighter. 

I'd go with Potable Aqua tablets, or Aqua Mira tablets for water purification

instead of a bulky bug suit, go with a small bottle of bug dope.

my knife is a small lightweight lock-back - a swiss army knife might be a good idea if you get one with a magnifying glass which might help in fire starting, and if it has a saw blade, forget about any other saw.

definitely a mylar emergency space blanket instead of a tarp

if your ditch kit is too heavy and too bulky, you will eventually tire of carrying it and do without - your bigger kit, if you go that way, is much better attached to your canoe with a biner - don't lose your canoe, but if you have to abandon it in the middle of a lake, you can easily unclip the bag and swim away with it.