Have you observed this problem/issue? I mean, have you actually had condensate leak into the coach interior, or is this only a concern at this time? Also, are you sure the drain lines are clear of cobb webs and debris? This is a common problem that results in excess water inside the roof unit base pan.

Something you need to be aware of about the Dometic system:
If the Dometic a/c's are original, you should have a 4-button Comfort Control Center (CCC for short) inside. Most converters used just one CCC to control all three or four rooftop units. The circuit boards inside each roof unit are specific to that CCC. These boards are no longer in production. Unless you have a separate CCC for each roof unit, changing one item in the system will require you to change the circuit board in all the other units you are not replacing, and update to a 5-button CCC for system compatibility. Also be aware, if you were to find boards that were supposed to be compatible with the 4-button CCC, there were 4 major revisions, and the clock speeds are not the same with all of the older "4-button system" units. Simply finding older components doesn't get someone out of changing all the boards. Just food for thought.