Yes, you can run one or the other of the A/C's, so if you shut down the "main A/C" you can run the bedroom A/C.
The point to remember is that you can use "up to" 30 Amps of power. If you are using, say 10 Amps with your reefer, converter and battery charger, you've got 20 Amps remaining. The "main A/C" uses about 15 Amps, so if you turn it off, you can use those 15 Amps to operate some other appliance in your RV. The bedroom A/C would be one of those choices......
Hope this makes some sense to you