Griswald, did you have the caster checked? We too had this fixed at time of alignment (this Spring) and feel this was a contributing factor to our over-steering issues. Wind/trucks still can be somewhat problematic, but on straight highway driving at speed (on a decent road), virtually no over-steering now.
Since Jayco said they would foot the bill, we went to a local truck garage that has all the heavy duty equipment for alignments and alike. They advertise RV alignments of all sizes (class A, B & Cs). Did the alignment, caster adj, and Hellwig adjustment. Even adjusted front headlights as needed.