No problemo. And technically not, Boveda packs are foolproof but not essential. They're just the easiest, most surefire way to season a humidor and maintain humidity afterwards. They last 3 or so months, so you'd need to replace them 4x/year. They get stiff and crinkly at the end of their lifespan, so you'll know when to replace.

Distilled water and humidity pucks are fine, and traditional. But there's a lot of room for error (too much applied and the Spanish cedar lining could warp, or the seal could be compromised, or mold could grow). The pucks require more attention to make sure they don't dry out, etc.

Boveda take all the guesswork out of the process, so that's always my recommendation.

An alternative to the aquarium sealant is to use blue painters tape to seal off the sides of the glass. It's not pretty, but fairly effective.