Most don't have one. In fact, standard impact wrenches won't even bust those loose. It takes a super heavy duty one.
If you want to carry a spare, find a spot for one somewhere. You'll need at least a 3ft breaker bar and a very good load bearing bottle jack. Also you'll need a heavy duty impact wrench socket that won't bust under the pressure.
Better yet, may be good to have Good Sam, AAA, or the like. :)
I feel the pain though as I prefer to do my own "surviving" while out there and not rely on services. The Toyota is not so bad, just takes an extra large 4 way. The bounder class A takes a 3ft breaker bar... And let me tell you, I'm fairly stout and the lugs make me feel way less stout.
If I had a pusher, I'd probably have a compressor with me. A high volume but low storage type - and also a MEATY impact wrench.