[JesseK]

We only put the bolt through 1 wall of the tubing. We use round socket or phillips bolts, and bore a larger hole with a stepper bit (not sure of its official name) on the opposite side for access. We have a magnet in case the bolt drops. We did this on our drive train last year, and on a pretty high sheer-stress piece in prototyping this year. We haven't had a single problem yet, and the drive trains had (have again this year) only 1/16" wall tubing. The key is torsional support.

It also saves us some weight (maybe 1lb) overall on the bot since the bolts are all 1" shorter.