Thanks guys, makes me feel a bit better... I think I'm still going to go with the steel braces though, just don't trust this thing anymore.
Made some minor progress, we got the euro-bracing on!
A little hard to see, but I've got 4" of bracing running along the top perimeter and then three 6" braces running over the top, front to back.
Once the books, clamps and tape comes off I'll take some proper photos. Didn't want to climb inside the tank before everything's had a couple weeks to dry.
On a funny note, after putting the braces on I noticed the piece of MDF I used to stand on, inside the tank still. Lol, guess I'll have to chop it up to get it out. Somehow I always knew I'd forget it in there. MDF make good aquascaping? lol
5 More tubes of silicone on the way... This puts the count on 24 tubes and I'll probably need more before the overflow's done. This time I'm going with SCS 1200... half the price and free shipping with some true union valves and clear netting I found online. From the info I could find online it looks like it's pretty good at adhering steel to glass as it's a industrial glazing adhesive. Doesn't stick to plated steel though unfortunately so I'll have to do a lot of prep work on the steel angles once I find 'em.
On the topic of silicone, when you google GE SCS 1200 silicone and open the official spec sheet, the logo on the top of the document says "Momentive". GE has been licensed and trading under Momentive since 2006, so it's either the same or close to the same stuff I've been using... just cheaper and more readily available!