Don't see the point. They don't reduce the amps needed while the compressors are running.
I ran two of my 15K btu units on 30A when I first got my Hughes Autoformer, (Joe, trust me, your not buying one of these $$$), and with the fridge running on propane, charger off, was reading 28A draw.
Couple of weeks later discovered one prong on a 30A extension almost melted off. This plug was ahead of the Autoformer, so I should have seen that coming
Have never bothered attempting running 2 HP's on 30A since!
Right now I'm hooked to 30A, about 40' of 50A cord, and 50' of 30A cord.
One 15k HP running, fridge, charger float charging 0A, and a LED TV, and satellite receiver running. Total 22A AC.