Great, thanks guys/gals. I didn't think to check the tube for specifications - good call. I'm using the same silicone, will double-check, though.
I've used masking tape for the baffle installs, and it helps - only if you can get a razor in to clean up the overlap. Since I should have full access, I will definitely be masking off the silicone areas.
I will lay the tank on its side for sure, although I'll still need a jig to hold the glass in place. Half the work in these jobs is making the jig! But that's how you get a good result, prep work.
I just got the drill bits yesterday, hopefully PVC arrives today. Will cut out the bulkhead holes, then install the overflow box. If all goes well, might even get that far this weekend!
Thanks again...I love this forum, you guys rock.