Generally speaking the anwser is no--15/20 amps plugs are about as low as it goes. There are adapters [pigtails or "splitters] that convert 50 to 30 and 30 to 15/20, but none that convert/combine two 15/20s. I have seen an adapter advertised that converts one 30 amp and one 15/20 to a 50 amp but am not sure how those work as you can have problems with your surge protector with multi-ground sources?????
Again, 15/20 is the bare minimum but if you turn off almost everything else [bat charger, hot water to propane, etc, etc, you may be able to get by with one A/C unit.
2003 40' MDTS
Garden Ridge, Texas