What about a backpack for his fishing gear? https://smile.amazon.com/KastKing-Fi...s%2C135&sr=8-4 Something like this looks easy to keep organized. Or maybe this because it looks comfortable and versatile for his back: https://smile.amazon.com/BLISSWILL-F...NsaWNrPXRydWU=
If he always take a cooler of drinks with him fishing, it might make more sense getting him a backpack cooler. Drink coolers can be heavy and bulky so however you can reduce the most strain makes sense. This one looks good: https://smile.amazon.com/TOURIT-Back...s%2C153&sr=8-3
" I object to violence because when it appears to do good, the good is only temporary; the evil it does is permanent." Mahatma Gandhi
"This is the ultimate weakness of violence: It multiplies evil and violence in the universe. It doesn't solve any problems." Martin Luther King, Jr.