Hi @rangewider,
This is well outside my expertise, but if you’ve already got an enclosure can you potentially have one without a depth rating that’s located inside the enclosure? I’m not sure whether that’s suitable for your application, but presumably letting the enclosure handle the pressure would allow getting a much cheaper one.
From the linked one, note that this point
could be quite important. Light through enclosures and water can get bent in somewhat unintuitive ways (there are a few relevant resources here).