There's another way to partially beat the crowds - be up at the crack of dawn. I lived near Yosemite and tried to avoid it midsummer but spent a week in June once and even there, I was out shooting photos at first light and had it mostly to myself until 8:00 and relatively light until 10:00. I was at Yellowstone last year and shot photos relatively near the campsite until 8:00 and then hit the road with the family. Of course we eventually had to deal with crowds and traffic but we could cover 30 miles relatively quickly and get to the area of the park that we intended to explore for that day. If you rent a scooter, I'd head out early to your chosen trailhead.