My egg boxes are sealed with Glad Press & Seal and then the lid on top of that. About Day 45 I take the Press & Seal off, but leave the lid on.
I don't have personal experience with the Hovabator - I heard of enough failed clutches in them, that I never considered it as a viable option for ME.
Some people have had success with them - hopefully you're not using the wafer thermostat that's in it and have purchased a separate thermostat to control it.
Good luck!