Yep, I cover myself.
On first visit I outline for patients here is what you do in emergencies; basically go to the hospital. Here is how you can reach me for 'urgent' issues, a dedicated Google Voice number for after hours. Same one I use to call patients back on the rare occasion I need to call patients.
I really articulate the role of sending messages through Luminello, and strive to be responsive to them. This has been the main manner communication line. So when on vacations I check at minimum twice a day. Lunch and ~5PM. If able I'll check more often. I'll typically bring my work lap top and log in for those. Other times I've just used my phone to log in address things.
Once while hunting, in middle of no where mountains, I keep my phone on vibrate, I did have one patient call that number. Basically side effects and just needed to reduce back to previous dose and not a reason to call me. Bad weather day, pronounced wind, trees were falling around me mid call.
I've been out of service before in some hunting locations, and fishing locations, and I just check once in evening. Which means - will go out of my way to find cell reception to do work check.
I do plan in years to come to possibly to round the world travel with ~24hr + time, and will simply just not worry about the phone. But assistant is seasoned and can put fires out for 24 hours.