Sandman, hold the phone...
I would not drill and refill. That *might* cause more crazing.
You have the same problem I had, it seems...
The fact that you have a metal brace puts you in a much better position than me...and you're close to some experts!
I went to So Cal Creations, they should be right down the road from you.
I picked up some 1x1 (about 5ft long) and then I went and bought #40 weld-on, which is a two-part weldon that is as strong, or stronger, than #4 and definately stronger than #16. It's goopy so you can run a bead. I'm going to run the rod the length of the tank in the top corner.
The main problem I have with #3 or #4 (I don't know anyone who stocks 3 anymore...) is that the solvent evaps and leaves gaps behind. You are more likely to either increase the crazing and/or make the gaps larger after curing.
Next time you're in town, swing by my place and I'll show you what I'm going to do. If I'm up in your area before you start, I'll take a peek.