So the tremolo cavity will require 3 levels of routing.
The heavy shaded area (where the spring mechanism sits) will be about an inch.
The lighter area is where the tremolo arm fits will be about half that.
The rest of the cavity only about a quarter inch.
The bridge studs are not open ended.
There are 2 screws that bottom out on the ends to raise/lower each end of the bridge.
The saddles also are individually adjustable up/down and back/forward.
This means the studs will not be removable via my preferred method.
As a work-around I'll drill the first holes to accommodate just the bridge without the studs. and once satisfied that it's sitting correctly, I'll enlarge the holes to fit the studs. (After the body has been finished).
cheers, Mark.