I'm not quite there yet, but almost. 18 y.o. DS decided to stay at home while attending university this year, instead of taking a gap year to travel or attending an out-of-town school. He's mostly motivated to stay in this city because he's involved in the music scene here, playing and recording with his band. In September, observing his friends who were living in dorms or apartments out-of-town, he admitted that he realized he'd like to try it himself. Since then, he's visited his out-of-town friends a couple of times. I wouldn't be surprised if he moves out within the year.
For the past couple of summers, we've left DS at home while we go away to our cottage for a week or so. He's had to stay behind for his summer job. I texted him once a day in the afternoon and we would exchange texts for a short conversation. That was enough so that he knew we missed him and that he wasn't forgotten and that he was okay.
We had dinner on Saturday with friends who have a son away for his first year of university this year. They Skype with him every Sunday and otherwise text or e-mail during the week. It seems to be the right balance for them. I think we would probably work out a similar schedule with DS if/when he moves out. For us, that's probably the right amount of contact.