Ok, forgive the CA and otherwise poor shot but I didn't spend much time and used a "meh" lens...anyway, happily, I was mistaken, the 17-50 does not have the lip that I thought it did, so you should be OK on clearance (I'd doubly verify but my Rebel II doesn't have a good battery right now).
Anyway, on the left is an EF mount, the other 2 are technically EF-S, but as you can see, the Tamron does not have the lens element past the mount that you see on the middle, kit lens.
I used to take lots of photos at late night events (AKA "Raves") and I found that 2.8-3.5 was just barely enough. I typically got the best results from my 50MM/1.8 FD on my AE-1 Program while shooting at F1.8-2. Attached are a couple examples, one at 1.8, one at around 2.8 with flash.