50 amp RVs may sound great but the thing is, the NEC (
art. 551.71) only requires RV Parks to have a min. of 20% of pedestals to be 50 amps. Upgrading above the min. requirements is very costly for a CG owner so unless you are going to a "higher end" or maybe gov't. CG, you will likely find it hard to find a 50 amp pedestal. And for older CGs/RV parks, the NEC required far fewer 50 amps which is why older CGs (like Thousand Trails for ex.) hardly have any, or even none. Has nothing to do with anybody "cheaping out" when building a CG.
I see RVs all the time at CGs having to use a 50/30 amp adapter. When you shop for a new RV, a dealer will never tell you how hard it can be to find 50 amps at CGs. Unless you specifically go looking for "higher end" RV parks before you hit the road, you will likely find yourself having to use 30 amps, esp. if you travel around a lot.
Low voltage is a common problem problem, esp. in the summer with a lot of RV-ers running AC units. As voltage goes down, an AC unit draws more current, the opposite of resistive appliances (toasters, heaters, etc.) and motors (120VAC). That's typically why breakers will trip when running an AC unit. Running small gauge extension cords (15 amp) will increase voltage drop and some cords are only 16 gauge which is not good to use.
An autoformer is a good investment. We just bought one as we have been at a few too many CGs with bad voltage. But - you won' get the full 3600 watts available if you had 120 volts without an autoformer (30 x 1200 = 3600 watts) and it may still be difficult to run 2 AC units. For example, say the pedestal voltage was 100, the available power would be 30 amps x 100 volts = 3,000 watts. And this does not include internal losses of the autoformer.
If there are 50 amps available in a CG and you have 30 amp service, it's a good idea to find a 50 amp site and use an adapter. 50 amp sections in a CG will be wired with heavier wiring. Had that problem at a Thousand Trails last year when voltage was way down at 106 volts before even plugging in. Tried another 30 amp site and still no good, then went to the 50 amp area and had excellent voltage close to 120 the whole time.
Another issue with 30 amp receptacles is that they are often in poor shape compared to 50 amps. If you have a choice and the 30 appears "iffy", use the 50 amp recept. and adapter.
It's important to turn off the pedestal power before plugging in. If you don't, the converter/charger causes an inrush current that causes pitting of the shore power plug blades. Over time, pitting gets worse and along the way attracts dirt causing resistance and heat and then a meltdown or worse. Resistance will also cause voltage drop, making the AC unit(s) draw more current, and in turn, cause the plug/recept. connection at the pedestal to heat up more. Ensure your plug blades are kept clean all the time. You will never know how bad the insides of a pedestal recept. are though.
Some folks can get two AC units to run on 30 amps, but you will need to turn off as many other loads as possible and you will also need good voltage close to 120 volts. You could try running 2 AC units on 30 amps somewhere where the voltage does not drop much (when using only a 25' shore power cord).
You *could* install a 20 amp power inlet on the side your FW and run an extension cord to the 20 amp pedestal breaker. All pedestals are required to have a 20 amp pedestal. You may still have voltage issues as the feeder cable size to a pedestal is not sized to run 20 & 30 amps together. I have seen some very expensive MHs running a 50/30 amp adapter with an extension cord out a window to the 20 amp recept.
This photo shows the worst pedestal we've seen at a CG to date. 100% of the CG was 30 amps only, and many had the 20 amp recepts. removed. The recept. was so bad, I had to use a stick to prop up the plug from falling out. Sometimes even if the voltage IS good, you don't want to plug into a 30 amp pedestal.... :(