I'm trying to do the same thing in my travel trailer. I use a disconnect switch at the battery due to some phantom loads in the trailer (it's stored indoors), so wanted a way to ensure that the panels were never connected to the controller when the battery was disconnected.
I use a Wanderer 10 currently, with a 12VDC relay (10A contacts) wired from the "load" terminals, and set the load terminal setting to "15" (manual). The external relay contacts break the + from the PV.
When the CC's powered on, the load terminal is always off. Pressing the Enter button on the front energizes the load terminals, closing the contact on the relay, and thus connects the PV panel to the charge controller. I've found no ill effects from using the battery disconnect while the PV was active (i.e. - cutting battery and PV power to the CC at the same time). BUT, this has only been in service for a few trips so far, so proceed with caution.