I take what I need to troubleshoot minor problems and to do minor repairs. For that a Phillips and slot screwdriver, wire cutters and strippers, needle nose pliers, small vise grip pliers, electrical tape, a couple 3' lengths of 12ga insulated wire, and a small digital VOM are the basic tools. Add in a few box wrenches for any battery cables and spare fuses for the panel and a small compact flashlight that I can use in tight spaces. The VOM is to check voltage and for continuity testing.
On several occasions I have had a small Crescent wrench and been able to remove the cable from a battery and prevented an electrical short from turning into an electrical fire.
I think in terms of what can be repaired while traveling and what needs to be repaired as opposed to what can wait until I get home.