Have you tried a crystal press, like...
I've got a cheapo one of these and have used it to replace bezels on all sorts of watches; the trick is to find one of the resin inserts that's shaped enough to press the bezel while clearing the crystal. That way, as long as you know you've got it lined up properly and therefore you're pressing down evenly, you can put as much force as you like into pressing the bezel home.
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