[aerohead]

I rode one of these from '72 -to- 80.'
I played around with gearing, stanchion clip-ons, and fairings, but could never really exceed 40-mpg on the highway. My brother's H-D Electroglide, 1,200 cc V-twin cold routinely return 55-mpg, 'loafing.'
The Honda 250 Enduro single might have been a better choice. With a little 'reserve' power, it could potentially accelerate around or out of an emergency situation, whereas the 125 would be limited solely to braking.
For safety, I feel that a 125 is inadequate. Off-road, okay.
Today I'd choose electric.