WOW.

This is totally incredible. I got a Rustler a few year ago and became quite obsessed with the mid-motor conversion (turns out, MM makes a huge difference and is much better).

I read 100s of threads/posts, and your idea is absolutely the most clever by far!
I went down the route of buying a chuckworks chassis, and it is fine - works well, etc. But your solution is so much more clever and elegant.

Please do post more details on the steering linkage, in particular, as I don't quite see how that all works, and of course, please do post running videos.

As for bodies, you might start with Rustler bodies (either stock or aftermarket) as they are cheap, easy to get, and give you lots of extra space to work around those mods.

Awesome work!