In article .com,
wrote:

[...]

3) Most importantly, is there an easier way to do this?

Dunno if this is appropriate to what you're doing, but waterproof
watches are tested with vacuum. They suspend the watch in a small
container full of water then draw a vacuum and look for bubbles. Has
the benefit of keeping the innards dry if there's a failure.
Of course, that's backwards from what you're doing, and only puts out
a single atmosphere at best, but they certify watches to 100M or so
doing it.

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