This is a pic of al the junk I can cram in my old Underwater Kinetics camera case. It fills several roles: Tools, survival and aft weight for solo flying. I put this in the aft baggage to improve the CG when I'm alone. It weighs in around 25 lbs. Most will fit into the backpack if needed. Lots of signaling gear, as it accumulates over the years. Emergency water and the minimal tools to fix most simple items.

Running kind of low on flares, aren't you? Probably a good idea to carry too many rather than too few-- I just (re-) wateched 6 days 7 nights with Harrison Ford and cracked up when the goofy gal shot their only flare off (into the top of a palm tree!) to signal an airliner steaming along way up in the flight levels.
FWIW I carry a small selection of hand tools, nothing too specialized except a Cessna gear leg jack-point made of 2 short pieces of angle-iron bolted together to sandwich the gear leg. Also carry a tire pump, spare t/w tire & tube, and a spare inner tube for the mains (850). Even if you get a flat at an airport, and can borrow tools and a jack, chances are that the only replacements available would be sized 600x6. In leiu of spare inner tubes, a small bicycle style patch kit would probably work to get you home.

Yes, kind of excessive on the flares. I used to have to replace them at the three year date code. So I have a lot that are out of date. They will still work till the end of time, usually. I actually let folks fire off some of them when I'm in the middle of nowhere for practice. My Boy Scout groups found it especially fun. Of course that was against a whole host of Boy Scout law. I also like to have a bunch of the pen flares to give a couple to each person in the group. You may not be the one to see the rescue plane. One of my buddies went down off Gitmo. Floated around for 12 hours with no raft, just his LPA. They knew his position, but a head in the water is actually very hard to see. He, on two passes, bounced a pen flare off the windscreen of the helicopter going overhead and they missed it. So they are not as effective as one might think. In survival school, they told us the best signaling device was a pistol with tracers. Shoot them directly at the bridge of the destroyer, they will notice you.