Assuming 14 feet between the axles, you would need 9 inches of blocks under the wheels of one axle to level your coach. I'm assuming the distance between the axles would be more than that, perhaps 18 feet? If so, you would need more than 9 inches.
I would built leveling ramps out of 4X10's, or larger if you can find them. I angle cut one end and drilled large holes in the other end to be able to anchor the ramps with spikes when on slippery grass and to hold the ramps together when I needed to use two of them. Driving up on the ramps is not going to be easy. If you use a 2/4 to put the spikes thru at the end, that will act as a stop to keep you from driving off of the end of your ramp.
Some friends have used bottle jacks or floor jacks to raise their rigs up, and then blocked it. That might be safer.