Well on the silicone thing. I used to work on R.V.s. Have you ever seen those giant rollup awnings? There is a little metal rail that a beaded end of the fabric slides into. You measure, cut, silocone and screw the rail to the side of the r.v. The roll up awning has enough tension in the giant spring inside to break your hands and arms. I have removed all of the screws from one of the rails and and then rolled out the awning with the only thing holding against the tension being silocone sealant. It made a believer out of me. Have you ever tried to pry off a valve cover or oilpan that was installed using silicone sealant? Once it dries you can take all the bolts out and throw them away. That stuff is strong. Its completley up to you, it is your tank and you should do what feels right to you. I would feel much safer with silicone than epoxy if it were my tank. Steve