I also have two rooftop ACs with a 30 Amp system. The generator is a 6.5KW Onan that produces 230 VAC - line to line and 2 legs of 115 VAC from line to neutral. The front AC draws about 17 Amps on a hot day.
When camping there are several options:
1. When plugged into 30 Amp shore power only the front AC will operate.
2. When on generator the front AC and the house are on 115 VAC Leg A and the rear AC is on 115 VAC Leg B. The rear AC is almost hardwired to Leg B except in the storage compartment is a 115 VAC socket on Leg B with the rear AC plugged in.
To operate both ACs on shore power I use a 50 Amp service with a splitter to two 30 Amp sockets. You can purchase these Y adaptors online. The house and front AC are supplied from Leg A of the Y adaptor and I use a 10 Ft cord from the Y Leg B to the rear AC plug in the storage compartment. You must use one leg of a Y on the 50 amp service for the house cable. Do not plug the house cable into the 30 Amp service in the supply box. This is because the supply box connects the 30 Amp socket to one side of the 50 Amp 230 VAC service to give you 115 VAC. Depending on which Leg of the 50 Amp service the electrician tied the 30 Amp service to, if you plug into the 30 Amp connector on the box and use a single 50 Amp to 30 Amp adaptor for the second AC, you may have the house and front AC on the same Leg as the single 50 to 30 adaptor.
With the Y 50 to 30 adaptor I get full power to the house and front AC on Leg A and full power to the rear AC on Leg B. This work just like powering everything from a standard generator with two Legs. It makes your unit look just like a normal 50 Amp service load. Use at least 12 guage for the second AC cable.