Do not put down 3-4" of 1" ball bearings that a MH will have trouble driving in. Put down a couple more inches of crusher run gravel putting a side slope to it so water will run off. Your jacks will be able to level the MH and jack pads may be necessary on the lower side.
If you can get asphalt road millings/grindings that are very black (very little gravel in it) and often is not more expensive than gravel. 3" of it will over time and summer heat bond back together forming an excellent surface. You can use the weight of the MH to compact it when put down and then again in the summer when it's hot and sunny.
