...Not sure why I am so afraid of running such high a high RPM for extended periods of time.
Because you are either well-informed, have great intuition, or both.
The dumb thing is geared to run at 110mph at the 7500rpm redline. That's too high an rpm/mph.
It really doesn't have enough power to run that fast and, in fact, peak power is at about 4500rpm.
It would seem to make some sense to gear the thing so that the fastest average speed that you travel occurs just a bit below the maximum power point. That lets you accelerate from that speed and you can gear down for a significant grade and maintain speed by bringing the rpm up.
If you normally would cruise at 70mph to git somewhere, why not gear the bike so that 70mph happens at 4000rpm? A gearing of 16/42 would do that nicely. When you done did git where you was going and need to gear down, the front sprocket can be swapped to a 15 or 14 in minutes. A prevailing torque nut, a wee short wrench, and flip-flop axle washers can make that happen real easy. I have my flip-flops set up for a 16/14 swap. @DPelletier
makes a good point about accelerated wear with a 14 but, in my usage, the 14 doesn't get enough miles on it to worry about it. Exaggerating a bit, I ride 300 miles to go on a 20-mile dirt road. I think Dave rides 300 feet
to go on a 20-mile dirt ride...