I use to carry a BUNCH of stuff, but have since reduced down to few select tools I use all the time. These include:
A hacket (yea - spelling :) ) It doubles as a hammer, and really have not used it for chopping fire wood in quite a while.
A ratchet and socket to tighten down my Satellite tripod. (only 1 dedicated just for this.)
A ratchet and socket dedicated to remove the anode rode in the water heater to drain at the end of every trip.
6 aluminum tent pegs to attach the Satellite tripod to the ground.
Extra barrel connectors to connect extra lengths of coax cable together for the Satellite dish.
An in-line satellite finder
OK, as you can tell, we have DISH Satellite.
I carry a tool box in my truck all the time. It's specifically set up for the camper, but I keep it in the truck 24x7. The contents change from time to time, but the basic "staples" are needle nose pliers, regular pliers, small socket set with ratchet (Yes, this is the 3rd ratchet), adjustable wrench, a hand full of zip ties, bungie cords, duct tape, flat and Philips screw drivers, tin-snips, a utility (box cutter) type knife, black electrical tape, extra pins for my Weigh Distribution bars, extra D-pins for my tongue coupler catch, and extra socket that fits my scissor jacks, a special socket wrench extension that's flexible to use for an override in the event the camper slides fail. And because we now have a camper with slides, and this little tool came with the camper, I'm now carrying an electric drill all the time too.
I also keep my winterizing blow-out plug in that tool box, just so I won't miss place it, the winterizing kit is actually attached to the water pump (which I permanently installed). I carry a T-style lug wrench (but never used it - except once on the scissor jacks when the scissor jack tool tool fell apart (The socket on the end is movable and the pin inside it broke and the socket fell off, so used the T-wrench to finish breaking camp.)
I carry a couple extra 3 way to 2 way adapter plugs for those rare occasions I plug something that does not have the 3rd ground pin. I carry extra radiator clamps big enough to go around my sewer hoses, I carry a couple mid-size carpenter's clamps, extra rope for our canoe, and a eye-glass tool kit in our emergency medical kit, which is really packed full of nothing but band-aids and wrapping gauze.
I know I've rambled quite a bit here. The weather is still cold and snowy in Indiana, and, after all, it is Sunday Afternoon, a lazy day, and nothing else to do but muse and let my mind wander off to reminiscing about the camper. Questions like this stir a glow in me!
So when think about tools, it's not so much how much you pack with you, it's how functional are the tools to you? Do you actually use them.
All the suggestions others have posted here are good. But there again, you need to customize your "stash" to your own needs. As time move on, you will change your "tool kit" also.
Good luck ... and this was really a nice walk down memory lane! Boy, I wish this weather would warm up!
