Yea, I don't get where you need to complicate keeping in synch with sag with more technology. Folks and their sag managed to keep track of each other before there was any of this current tech, just paper maps. I think that discussing the route and next meeting spot when together is all most do.

In most cases where there are a lot of road choices, like in or near town, there is a cell signal. Out on the open road your route is unlikely to be very complicated. Also most folks I know who use sag are never very far from them. The leave camp and typically see them down the road for second breakfast or at the latest lunch and again at least once for a break in the afternoon. Most of the folks I made friends with on my tours seemed to meet their sag 3 or 4 times during a 60 mile day. I'd wager they were seldom unaware of pretty close to exactly where each other were.

Also if they wanted to be in touch where there was no cell signal they were in range of Family Service Radio or walkie talkie most of the time. I don't recall any of them bothering with more than the cell phone though.

I have no first hand experience with using sag, but have befriended and hung out with other folks using sag on long tours. Some of them we camped along side and spent time with quite a bit.