One tool I've found incredibly helpful is one of those long, flexi grabbing tools WITH A MAGNET.
I take spark plugs, hex keys, a small set of 1/4 sockets and ratchet, some 1/4, 3/8 and 1/2 tubing, hose clamps, screwdrivers, cable ties, duct tape.
Admittedly I just rip local lakes. But...