You have perfect pavement in Pennsylvania? Never any potholes? They only thing that makes a 20" tire bike marginally acceptable would be the fat tires. Fat tires do eat power, drag considerably.
Buy yourself a bike with actual wheels. 26", 27.5", something that will bridge a pothole with 2" tires. If there aren't potholes there are pavement separators that stick up 1 1/2" cm. Hit one of those at speed, scrub the road with your chin.
BTW the 3 class system legislatures have passed has eliminated US stock of 1300 W geared hub motors. I had one, wore it out. Now all I can get are 750W, that won't drag groceries up a 15% hill without maximum effort on the pedals at 1 mph. If I want to shop for groceries a week at a time, I'm going to have to buy a car. Each round trip to the store is 7.4 hours on a windless day.