On my trailer, I have two gray tanks and a black tank. The toilet and shower drop into the black tank. The bathroom sink into the rear gray tank. The galley tank at the rear has a gate valve and the drain connects to the other two tanks (one dump valve). Since I have to crawl under the living room slide to get to the galley (rear) dump valve, I leave it open when camping as well as the other two (black & gray) dump valves and have a Valterra twist on dump valve on my one sewer out and connect a hose to it. When I want to dump, I open this last valve and all three tanks dump via the sewer hose to the sewer fitting.
https://parts.unitedrv.com/products/...nt=Catch%20All
Oh yeah, Keystone buys thos monitor panels from one company and they seem fairly universal; all will have idiot lights for functions that may not be there. My monitors are not accurate and I don't really look at them.