Yes, it's Flash. Yes, it's unconvential. But it works, and I love Flash.
Here's a better sketch (done with Flash!), to give a better idea of how this'll all work.
That's a lot more cover. The trench won't be sniper friendly anyway, seeing as right now the battlements give a very limited view.
EDIT: I wanted to try and avoid doing this, but maybe it's necessary. Do you think I need to add a tunnel going under the map? From the right/top/small/empty tunnel down to the trench, as well as add a ramp and make a building on that side player accessible? That side of the base just seems too empty, and if you think snipers will really be that big of a problem....