I would have any tool
with me that I knew how to work and how to do what ever kind of repair that I felt competent to do that I could forsee a need for. In other words, do you know how to read a multimeter? If you know how to read a multimeter and conduct electrical diagnostics, then that tool would be of invaluable aid. If you don't know how to read one, then it won't do you a bit of good, will it?You mention that you carry a spare impeller, so having the tools to get to the impeller would be of aid if you were to undertake that task, don't you think?Most of us carry a wide assortment, it just depends on you skill set. I carry spare taps and dies, do I use them, nope. If I need to, then I have them with me. This will be your call Captain. Good Luck!