Recon - C4 feels inconsistent; clear mines/IR smoke/APS shouldn't remove it.

I agree. Placing 4 C4 and running away to press the trigger is difficult and risky. Run around the map to the back of the tank as it stops to repair, avoid or kill the repairman silently, hope nobody pops out of the vehicle spawnpoint and sees you, and it turns out there was an invisible puff of thermal smoke still remaining ten seconds later that deletes your C4 and now you don't have enough to kill it.