Adding an OnOff parameter to Trigger Crate in JCS would be no trouble at all, but it would absolutely require JJ2 support to work. Seriously tiling layer 4 would be hell in multiplayer levels (even a single event would fill up memory to infinity), make warps nearly non-functional, interact poorly with JJ2's internal position numbers (which reset to negatives after 1023), and who knows what else. A "seamless warp" event would be cool, though, and achieve the same effect without any of the problems.