The "truck" version of the chart is PER AXLE. The "RV" version is by Corner LF, RF, LR, RR... They do this to affirm the finding that RV's tend to be loaded unevenly side to side. So they express Corners instead of Axles. And, Dual does not carry twice the load of a Single. Your front pressure would be 55-psi, and your rear axle is overloaded, so 80-psi there and try to shift weight forward.
Coach may not have enough wheelbase. This happens when a builder tries to but a walkaround queen rear bedroom on less than a 31-ft coach.