Suggest you get a regular Dometic Brisk II 13.5K btu for your bedroom. Most use a 13.5K btu in the bedroom although power requirements (draw) are not all that different for a 15K unit. $539. This is what I replaced our original A/C with (also Dometic)
https://www.pplmotorhomes.com/parts/...tioners_B57915
Your ceiling is already wired and braced so you will essentially be hooking up the AC voltage. You will need to control the A/C unit with a lower unit which is plug and play with the unit above. You will need to turn it on and off at the ceiling mounted controls but won't need to worry about two zone wall mounted controls.
https://www.pplmotorhomes.com/parts/...ls_3314851.000
This thing costs $70.
If there is any ducting up in the bedroom, you can block it off or leave it connected to the front unit. If there is wiring to wire the 2nd A/C into your wall mounted thermostat, it is likely plug and play and the thermostat will be capable of two zone control. If you are not sure, call an INDEPENDENT RV TECH and go over this with him. Install should take less than an hour. Camping World is likely not where you want to get this done. It also makes sense that the tech is Dometic certified so the warranty can take effect. If they are not, Dometic may not stand behind the new A/C if there is a problem. The Penguin unit is lower/more compact and costs about $300 more than the BRISK II.