There's a spec published on how much the A/C's amperage draw goes up when ambient temp is above their baseline. As I recall base was 90*F or 95*F. I'd guess your genset's amp delivery capacity will go down with extremely high ambient temps too.
Is something else running, like you left the Water Heater on AC power? You have a 6000W genset. Impressive BUT when you're on properly wired (not "fake 50") shore tie you have twice that, 12000W to work with.
RV heat losses are bad enough sitting still. Running THROUGH that 100*F+ air has got to be rendering the losses staggering.