Before you invest in a tote, give it a quick test at the store. If you can bend the lid in half without evidence, it will work. If you can't bend it , it will work. If it snaps, and little shards fly everywhere, you didn't want it anyway.
Silicone can change the geometry of the mating surface, . Use caution with other products. Some gaskets are true rubber, petroleum products are out.
Have you checked the clearance between the lands? I have seen fittings ( intended for thicker hulls?) with over length male threads. The bucket was so thin I ran out of female thread before I had ample compression on the gasket. If this happened in your case, the gasket could harden up , shrinking over time, accommodating a leak down the road.
Is damn tricky business. Really, you only get a small portion of the span of the gasket for contact. The smaller the plumbing, the lower the tolerances.
A thermostat housing has two bolts running through the gasket- those suckers line up every time and don't leak !