[JRTJH]

You pose several questions, some of which depend on how you address other parts of your questions....

Yes, you can plug a 50 amp trailer into a 30 amp power source. You'll need a 50/30 amp "dogbone" adapter to make the connection. If you do, you'll only have 30 amps available. What that means is that even if you have two air conditioners, chances are you could only operate one of them if you're on a 30 amp source. You'd probably need a 50 amp source to operate both of your air conditioners. Typically, two air conditioners won't work on 30 amps, but you may "get by with doing it" depending on what else is operating in the trailer and the outside temperature, voltage drop in the park system, how many other campers are using power, etc. In other words, there's a lot more to available power than just "it's a 30 amp source".....

That said, it's usually cool enough "when sleeping" to only need one air conditioner. So, you should be able to "get by" with 30 amps and still "sleep cool".... Even if you can't operate both air conditioners, chances are one will be in the bedroom and one in the main living area. So it's possible to "work around" the comfort issue by closing off the bedroom during the day and operating the main area A/C. Then, even if it doesn't cool down by bedtime, turn the main A/C off and turn on the bedroom A/C, close the door and you should have a "refrigerator" in short order......