How about a stock 18" front wheel with a used 225-45-18 tire (instead of 225-40) installed on it, thus being 26" diameter like the rears instead of 25" like the fronts?

Has anybody tried this?

This would:
1) Be approximately the same 26" diameter of the rear so you do not put too much wear on the differential.
2) Be the stock width if used in the front (it looks like the extra 1" overall diameter-1/2" at the tread at any one point-will clear the bodywork for most of the steering movement).
3) Live much longer than a temporary spare if you are many miles from home.
4) Not need any special length bolts like using a MB spare.
5) Be inflated and ready to go right when you need it beside the road.

Thoughts anyone?