A thought...

[Fitz]

There was once a destructible gate which could be opened and closed on hidden cave. It wasn't such a great idea. At that time, there were 2 spawns (one in te cave and the other one just next to the current players spawn). The team had to destroy the gate in order to cade in there (it was the only spot where we could cade). Most of the time, we wiped wave 1/2 because we didn't have enough time to cade in.
I think later on, we could open the gate without breaking it. Most of the time, some guy (trolling maybe?) closed the gate with half the team outside/inside leading to a wipe but that's like 2 years ago? I do not know if that kind of map could suit the actual game mechanics (timer..).

I don't think the timer had been implemented when we had that map so yeah as theres now more time before the first wave and sped up cading in that prep time I think it might be more viable now even if it is still open to trolling, I don't know if there is a way to make it that when you've opened a gate it can't be closed, failing that then you'd just have to make it destructable