When I was campaigning the HP-11, I carried in the glider:

1/4" drive socket set, 1/4" through 9/16"
Medium-sized flat-blade screwdriver
Sharp #2 Phillips screwdriver (these get dull faster than you think)
2 feet of .041" safety wire
Wrenches 3/8" and 1/4", box+open ended
Two allen wrenches (for flap handle and instrument panel removal, don't
remember the sizes)
Tube of lithium grease

In the car or trailer, I'd usually carry:

Full 3/8" socket set
14-volt battery drill
Honkin' huge Crescent wrench for O2 and such
Fiber mallet
Pop riveter with several sizes of Monel pop rivets
Volt/Ohm meter
Crimp terminal kit with lots of red-size terminals
Lots of tie-wraps
Lots of wire, 22awg through 18awg
Various AN3 and AN4 bolts and AN395 nuts
A pint or so of epoxy