I say don't change your setup for them; get a dedicated device… consider a tablet. Having two devices is a pain, but it'll improve your work-life balance when you have to actively decide to carry it. You'll also never accidentally send something personal to a coworker.
I use an older iPhone in airplane mode. I get over a week of battery life. I forward calls to my personal if I'm away from wifi and on-call, and they do not get my personal phone number.