I dont have your model but to me it seem odd to have TWO inverters. They should upgrade to one (Maybe 2000 watt?). Perhaps insist on larger battery bank?
All of the gernerators I have hear on these RV's are very loud. So yeah - like 8am till 10 pm for sure for run time (but 8 to 8 would be ideal if you can get away with it).
If your not running your AC it should only take a few hours to recharge your bank after using all night on 12v. So like 8 till Noon then you should be full and maybe run again 6 to 8pm to top off for the night?).
2017 Axis / 25.4: Big Foot Levelers, Aims 1200 Watt inverter, Ceramic Window Tint, Full River AGM 6V batteries, Front Hellwig Sway bar / Rear Track Arm, Safe T Plus Steering Stabilizer, PD 4655 converter, Hard Wired Surge Guard, WEboost + WiFi Ranger, LED Headlights/Driving lights, TPMS, Surge tank, Tornado flush, Viair Compressor