With the avatar dune buggy weight was precious. Every ounce counted. My tool selection process was to put an empty tool box in the buggy. Every time that I worked on it, and I did 100% of it's work, I used the tools in the tool box. When the box didn't have the tool needed it got added. It took a while, but eventually the box had exactly the tools needed to do anything required and no others.
I have a set of "Mr. Goodwrench" jumpers that are a small wire gauge and aren't heavy or hard to carry. They have surprised me with how effective they can be. All three off-pavement capable vehicles also carry booster packs. Two are XP-10's and I'm impressed with those (one started a 12 valve Cummins with flat batteries), the one off-brand unit not so much.