You should have already observed and know how much you lose per day. If you can’t leave it plugged in, it’s a matter of simple multiplication math to derive at what your starting SOC % needs to be, in order to leave it for X many days and still have a comfortable margin. Turn off as many features as you can: like proximity and gear guard, as well as limit number of remote check-ins while away.
Less than 2 weeks gone I leave my Gen 1 R1T unplugged. More than 2 weeks I plug it in if I can. I lose about 1% a day so it's easy to predict how much charge I'll have left when I get back.