Ouch. I feel your pain!
For what its worth, my two tanks have beckson deck access plates installed. The plate housings are held in place with silicone but the inner part is removable by unscrewing. There is a gasket in the piece that unscrews. When I bought Luckness both tanks were leaking at the gasket - I bought new plates, kept the inner portion and used them in place of the older ones, and they have been good. I bought the clear plastic version of the plate hoping to be able to inspect without unscrewing, but that doesn't really work as moisture gathers and you can't see through them.
PSC 37 #234.