We have a 15,000 BTU single air conditioner and 30 amp service. We've been running the air all summer (at home and when camping). The camper is powered and air on 24x7 this year. No problem at all.
Now, we do take some precautions so the 30 amp breaker will not pop in the garage or at the campground pedestal.
First, we run our water heater on propane. This removes electric draw on that 30 amp availability. With the air running, we have no problems running any thing else at the same time; televisions, lights, anything plugged into the 120 volt plugs, electric coffee pot.
We do not plug in electric skillits or our electric griddle through the camper. We have found one griddle or electric skillet will operate OK, even with the air, but if adding much more, the breaker will pop. So, considering we almost always cook with an electric griddle and an electric skillet, at the campground, we always run a separate electric 120v cord from the pedestal. At home, we cook in the house or our Smoker BBQ.
Basically, you have to manage that 30 amp. Recently, when running the microwave, we've been turning off the air-conditioner. It only popped the breaker once, but we decided not to do that any more. So for the few minutes we run the microwave, we shut off the air conditioner. Then when done, turn the air back on.
You've got to remember, you have only 30 amps, you have to manage that 30 amps. But if you do, you'll have no problems ever popping the breaker. If you do pop the breaker, you just turn something off and reset the breaker and move on. No problem.
Another remember: The converter in your camper takes some of that 30 amp. So does your refrigerator if running on electric. So does your water heater on electric. Your television and any electronic devices plugged into a wall socket also take part of that 30 amp. If you have a radio or television plugged in, even when turned off, there is still a small amp draw. The amp draw is on everything you can see, and everything you don't. So always be aware of what is using 110 v and part of that 30 amp availability.