I got my ez pass in Ohio. I can go online and change the license plate that has the ez pass in it. I just tried and I can log on to my account from my phone, so you could put in the license plate of the rental.
They do charge you a fee per month.
I don’t use mine but a couple of times a year but once the ticket didn’t come out and I nearly got very stuck on the PA turnpike. It’s a long story but I decided it was worth the monthly charge for me to not have that happen again.