Make him an ond fashion Situpon. Makea square block 18x18 sew a 3"saching between the layes fill it with scraps. He can take it anywhere and sit in it. If he is a fisherman, hunter use waterproof fabric on one side.
You can put a zipper on one side to fill with things. put a quilt inside for a shoulder cover up and always put his special treat in it and a love note.
Add a handel or shoulder strap. He will love it.