Hi, as you can see from my profile, I have a lot of experience with Chrome Extensions.
My idea is to make an javascript file in which you would input the calendar names which need to be shown all the time. And extension can check if these calendars are visible each minute, not hour as you said, it's not problem at all.
In my offer I've set a deadline to 3 days, but it could be done quicker, maybe even tonight if you accept my offer and milestone quickly. I've set it a little longer because I'll maybe have some obligations tomorrow, so just in case.
Regards, Stefan