Wow, that sure seems like some out of the box thinking on spacing the wheels out! Had you ever seen that done before, or did you invent those spacers all on your own? You're certainly right that it will give you lots more stability on sidehills, and who wouldn't love that.
Are you worried at all about the extra stress on the axle bearings and the axles? It would make me nervous, but hopefuly the axles are tough enough to take it. Really profesional looking job on the spacers.