"My Progressive Dynamics 9180 draws 1,000 watts"
It is rated at 1300w. It has a PF of 0.7. So it pulls 1857 VA from the 120v supply.
That Yamaha can supply 900VA continuous. A 55 amp converter will pull about 1380 VA, so that generator is limited to maybe a 40 amp converter briefly, but more like a 35 amper for a longer run time..
OP, you can run the two chargers at the same time from the big gen, and the two will add their amps as long as their voltages are about the same. If your converter will only do 13.6, but the charger will do 14.6, then the batteries will only see the amps from the charger, once battery voltage reaches 13.6 and goes up past that.
You want both chargers to be at 14.x
