I love thid idea, I think its to long, if you could shorten the frame you'd fix the turn radius. This is an outstanding idea, i wish i had the resources to build something like this.

I use those mowers for my business and have done some work inventing a small walk behind boom sprayer. This would be a good set up for that as well. Spraying fertilizer and weeds remotely. I just want to know how much the WALL-E that you bolted to the back is?