Dale,
The cheater adaptor will work very well if you have 2 separate 30 amp connections. It will give you a total of 60 amps for your 50 amp system.
If you can not connect to separate 30 amp connections and you have to run on 30 amps, just watch your amp meters to see how much you are drawing and turn off accessories as needed. You will probably be able to run 1 AC unit off of CG electric; you could always run the other AC off of the inverter.
When we were in Yellowstone (June) it was very cold at night. Don't think you will be needing the AC units, but you never know. Enjoy your trip
Tuga & Karen Gaidry
2012 Honda Pilot