I have a newer-style Makita 18V 1/2" impact (lithium ion battery). I didn't buy it specifically for the RV, but I do take it with me anytime I travel. The key is to get the full-size version, not a compact. For example, I think the compact versions of the Makita and DeWalt have about 180 ft-lbs torque (tightening), whereas the full size versions do about 345 ft-lbs or so. I have tightened bolts/nuts with it and checked them with my high-quality air impact (just for the heck of it), and the air impact couldn't tighten any further. I carry 3 diffeent size deep well impact sockets: 7/8" for truck wheels, 13/16" for camper wheels, and 3/4" for the stabilizer jacks. I don't always take the charger with me, but I do take 2 fully charged batteries.
I also carry a 10-ton bottle jack. I'll be upgrading the stabilizer jacks later this week, and since the old ones still work, I'll throw them in the front basement compartment to also help if the situation becomes desperate. I don't carry around any extra wood or pads, other than what I oridnarily carry in the camper for chocking, leveling, etc.