No worrie with that... i am in teh same situation as you and i have installed a 20A breaker circuit and also a QUALITY SURGE SUPRRESSOR protector to protect the Zero charger against voltage peak and spike. this will garanty you that your Zero cahrger will last longer. I also did that with my Maytag washer to protect the $$$ electronic iside.
What make breaker to pop when you have a garage door opener is the inrush current when the induction motor start.. then the stabilized current ls way lower.
Anyway... in all situation.. the worst that could happen is that you hit the garage door button while you forgot that your Zero is still on the same breaker and charging... and pop it...
The solution: reactivate it.. lol.. if you find that to avoid that few time it Worth paying 700$ of electrician fe.. it,s up to you but personally it hapenned to me during the 2 first years that i own a zero and i'm still able to sleep every night without any nightmare
Oh.. and .. personally i am more confident about myself installing a 20A circuit in my garage than any electrician.. i saw a couple installing stuff and they just work too fast and dont pay atention to every détails like i do....
Doc