OK, I had the same measurements, taken before I had fully loaded the motorhome. I felt it was too close to out-of-spec, so I bought a 2-inch drop adapter:
2 Inch Rise/Drop Accessories and Parts | etrailer.com
With a fully-loaded motorhome, I was down to roughly equal heights, maybe 1" high at the motorhome end. I left the adapter at home (too heavy), and proceeded to measure the heights at many stops until I was sure that the difference stayed within the plus/minus 3" towbar limit at all motorhome load conditions. Most of the time the difference was 1" or less.
If it wouldn't cost an arm and a leg to ship it I'd sell you my adapter. ;-)