I'm one of the old codgers who built plywood tanks 30 years ago; made a bunch of them using a 2-part epoxy called Palguard. The stuff was bulletproof, and glass was installed simply by laying down a big bead of silicone, lowering the pane down, weighting it, and then running a "safety bead" all around the edges of the glass. Never scuffed the epoxy, and had no internal frame supporting the glass. Worked beautifully, tanks lasted for years. One in particular was still in service at least 15 years later. It had had a few repaired areas of epoxy inside, but the silicone seal remained strong.
More recently, I built a 120-gallon plywood tank almost exactly 2 years ago, and this time I used Pond Shield. Much nicer and easier to use, virtually no fumes, applies fairly simply, good coverage. I adhered the glass using the cheap GE silicone...Silicone I? Same routine: no scuffing of surface, no supporting internal structure, just glue the glass to the epoxy, wait a couple days, add water. Two years isn't the sort of long-term experience I had with Palguard, but I think it's long enough to safely call it a success.