It looks like there's no easy way to do level design. Trying to get the game to automate at least part of it would slow the game down greatly, due to all the scripts that would need to be active at the same time. Automating the tile placement would work for smaller games with smaller levels, but with the plans I have, that's not going to work.
I do have an idea, though. It's not going to make level design too much faster, but it will at least speed it up. That's the hope, anyway.
It will make editing a mistake or changing a detail a lot less frustrating, at the very least.