Running an Onan QD Generator into either a GridBOSS or FlexBOSS18/21

[easyhouse]

I'm looking into installing both a GridBOSS and a FlexBOSS21 with solar panels and EG4 Battery (with FP&L Smart Meter-GRID). My concern is that I would like to use my Onan Quiet Diesel (QD) 7500 generator in my Recreational Vehicle (RV) that have two out leads of 120V (single phase - not 240V) at 35 Amps. The 2-120 Volt leads have a common ground. If you measure the voltage of the two leads you get 0 volts.

Can I use this generator into either the GridBOSS or FlexBOSS21 when the GRID down and I'm low of batteries at night?

Thank you,