as one of the two HPs on my team, i think the 10 second limit is cool, cause we can BARELY stack 8 in ten seconds, and doing other combinations is even more difficult, though possible.
I've never tripped over the barrier myself, but i do go running back to the pad to make sure our autonomous turns on, basically flying through the open gate with a sort of running jump and landing on the pad
One of our human players did fail to get back to the pad in time, and our autonomous period was disabled. They didn't disable us for the entire round though, so I don't know what's up with that.