1999 HR 30amp With 2 ACs

Alternate thought: your genset has sufficient power to run both A/C units internally. Try checking the genset and ensure BOTH 30- and 20-amp circuit breakers are set. The check to make sure whether there is a "select forward or back" pointer switch (mine is in the bedroom wall) is set to "back". On genset power, start the aft A/C unit, allow the voltage regulator to adjust, then turn on the forward A/C.
Also, if you have an external plug set up, mine has a plug that connect the genset power that has to be plugged in to use genset power on both A/C units.
Hope this helps...