This talks to riding a real bike:
You’ll get used to it. I don’t have a Zwift Ride, but rather a hefty big Kickr Bike, I set that on a rocker plate (KOM cycling).
Trying to get used to cycling out of the saddle will help a lot with comfort. The rocker plate also helps with that.
With more practice you’ll be like the guy riding up Col de la Madeleine, dancing on the pedals. 
Someone I used to train with would do 3-5min intervals riding out of the saddle.