That seems like a very good list and you have put a lot of good though into your needs and the demands of your route. My suggestions would be:

1) Adding ibuprofen if it's not already included in your pain killers category. It can be great for sore muscles and other minor joint pain on a long multi-day walk.

2) Would you consider adding a small can of dog-repellent or pepper-spray?

3) A large Ziploc or two to keep your maps dry.

4) If you are actually considering swimming a (wide) canal, you will want a dry bag to keep your goodies dry.

5) A back-up compass.

6) I would add something more palatable than datrex bars -- but I wouldn't have to carry them as far.

7) I don't believe the Aquamira Frontier is very good at filtering out pathogens and would consider better water purification options besides the Porta-Aqua tablets (such as Micropur). Have you scouted out water sources for your route (beyond the obvious canal)?