A small 3-4 ton floor jack won't cut it. You need at least a 12 ton bottle jack. Reason for a 12 ton...it's a lot easier to pump it up, especially over a smaller 6-8 ton jack. The leverage on a 12 ton is very easy, especially when your in an akward position under the motor home.
How do I know? Tried the smaller jacks, and 12 ton works perfect.
A piece of 2" x 12" x 12" underneath works just fine.
And rather than carrying a huge spinner lug wrench, I carry a 1/2 inch drive Kobalt electric impact wrench. Has plenty of power to take nuts off n on. If your on the road, just use generator for power (of course, if no genny, lug wrench is necessary).
I also carry and have used a Camco Tire Changing Tool, part #44511. It works great to lever the tire/wheel up to the wheel studs.
Have and carry this stuff, not used it on my rig, but have used it twice on the road and in a campground to help others.
Grumpy