Thanks, but avoiding an interlock is exactly what I was looking to do. My original plan was to make an interlock that disconnects electronically when not in use, but when I started working on that, I figured it would take a lot of time to get it totally right and reliable, so if there's an off-the-shelf solution that negates the need for it, even a fairly expensive one, that's preferable. The batteries inside the box are a several hundred dollars each (and there's a couple of them), so this has to be reliable, not just to save the connector, but more so to keep the batteries from being over-discharged.
Looked at wet-matable connectors, though those do exactly what I want, it looks like all of those are designed for high pressure (and do have the "call us for a quote!" prices to match), so I will probably have to do this myself.
edit: by do this myself I mean the interlock, not a connector.
Thanks anyway.