Personally, what has worked well for me when doing solo c4 runs is to have patience. I drive as close as possible to see what they're up to and wait for any tanks to leave the base. Then I'll sneak in. Same thing for placing beacons. If I can get in with an APV and get the beacon placed then the building's gone because the APV will usually take enough damage for me to sit on the beacon until it's too late for them to disarm it. Hotwires smoosh nicely when they try to come disarm it.

I don't do APV runs a lot though, since I'm usually the only one on my team that recognizes the need for defense.

As far as same team vehicle stealing.... almost the most frustrating thing since they're supposed to be on my team. One time I just bought a mammoth only for it to be mangled by a rogue flame tank before I could get to it. While I was repairing it, it suddenly drove off.

The most frustrating thing is to have a teammate purposely destroy your own buildings in a friendly fire game. The culprit easily sticks out with their score of -3500 or so. This server is also laddered so most people prefer not to destroy their own buildings. I don't know how it's laddered, since it's also friendly fire.. but it was.