Phoenix Cruiser has the 50A and two A/C upgrade for most of their models. I'd make sure to get the proper generator (5500 watt Onan with one 20A circuit going to the second A/C and the 30A circuit feeding the rest of the coach.)
I live in Texas myself, and to make sure your rig is habitable in the summer when we get weeks to months of temperatures above 115 (like last year), having two A/Cs is critical.
Plus, if you can only find 30A and the weather isn't blistering, I'm sure there are ways to turn off the second A/C.
You might be able to convert your 30amp to a 50amp.
Replace the cable, from 30to 50, the original hook-ups are kept, except the ac, whitch should have a cirquit braker, this braker is no longer used, a separate box with a braker, is installed and the ac wiring, is transfered to this braker, the second leg of the 50 cable, is conected here, you now have the AC, on a dedeicated cirquit.
The other solution, is to add a second air, and a separarte cirquit with a braker, to the new 50amp cable, second air con, goes where you have a vent, it isnot very dificult, to run cables to the air con.
We spend summers, in Desert Hot Spring, noth of Palm Springs, temps are normally 102 to 118+, with only one AC, the aircon is on 24/7, it is not shut down for three to four months, we have "C" class.
Most Class C's (new) have an optional upgrade to 50 amps. In the heat of Texas I would get the 50 amps and 2 A/C's
It is better to have 50 amp service and two AC's if you plan to camp during the summer in Texas. I converted my 30 amp fiver to 50 amp and added the second 15k ac unit to have a cool place to spend the hot summer afternoons.