Construction with gussets and bolts

[Joseph Smith]

I've been investigating some new design and construction methods that my team hasn't explored in the past, and I really want to try assembling the frame and important structures with machined gussets and bolts. I have a few questions for teams who have used this construction method. In this scenario, I'd be using two gussets, top and bottom, to create a 90 degree joint between two lengths of rectangular aluminum tubing, all 1/8" wall thickness.
1. Is it better to put a long bolt all the way through and use a nut on the other side, or to tap the gusset and tubing and use shorter bolts?
2. If a bolt all the way through is used, are large washers needed to spread the load to prevent the tube from being crushed?
3. If the parts are tapped and a short bolt is used, would it be preferable to tap both the gusset and the tubing or to drill clearance on the gusset and only tap the tubing?
4. Is locktite a necessity with the tapping method?
5. What has been your overall experience with this method of construction? Pros/Cons?
Thanks!

I should clarify, with the pretapped method, we would be using machine screws or something of the sort.

Clarification #2: We have used a lot of rivets in the past, and do like them for certain applications; however, I'm specifically interested in trying out bolts on the critical parts of the frame- primarily drivetrain- where it can see a lot of stress due to collisions or hard driving. These would be parts that we shouldn't ever have to disassemble or replace between matches (fingers crossed) so I'm not really concerned about the speed of installing/removing them.