OP,
Like most people have mentioned, you should not worry about anything with the Glock barrel. The factory recoil spring is super strong and the most reliable you can find for it. No need to change it. I have seen people changing it and having performance issues.
As far as a load for two legged critters, you don't need to go the extra mile, a good factory 155gr, 165gr or 180gr would do well. I prefer 165gr.
Your kayak plans sounds like fun. I hope you have a great time!