I've found that the easiest option is just to buy my own portable transponder. You can get the UNI transponder from
Amazon for $15+tax and it works in 19 states, with no monthly fee if you register it with CSX in Florida. (Yes, including most of the Northeast.) I do find that it's wise to tie a colorful bit of dangling gift ribbon around it when using it in a rental, so that I don't forget to take it home with me, especially since I have the black one that is harder to see.
https://www.cfxway.com/uni/
I leave my transponder on my fridge door when I'm not traveling, because we don't have tolls where I live. I have to walk right past the fridge to get to the garage, so that way I can easily grab it on my way out. (It has suction cups.)