I would endorse the jcb thing, we bought our place in 2007, an acquaintance had just finished a self build and had a jcb to get rid of, it wasn't something I'd thought of, but I bought it, and it has to be said it has saved us lots, but mainly compared to hiring its just the fact that its always there, you don't have to do jobs in a big rush , you can pop out and do a bit any time, in fact I'm off out now to shift a bit of soil, and a 1 ton bag of gravel ! It great stress relief after a day at work too. (Except when you dig through your own water pipe ! But that's another story.)
I've looked at your aerial photo, and mock ups, looks great.
Ps. I did have previous experience of driving a jcb from my youth working on my neighbours farm...