speaking in Old Mechanic's place: MPH at redline and cruise at redline/2 (?)
Your exponential gear spacing would be strong off the line, but suffer in passing situations. How about a low that's low enough to allow normal 2nd gear starts with a "stump-puller" gear in reserve. Or an inline overdrive or electric motor replacing the transmission tailshaft, and if you have a live rear axle, ultimate control with one of these:
