Mom, I understand your angst. But heres my advice: Relax a little. I assume your son is a competent cyclist, or else he would not be attempting such an ambitious uh, wait. Did I read this right? January? As in, the month that follows December?
You cannot bicycle cross-country in January. Not even if you do the Florida-San Diego route, via Mexico. Theres too much chance for lousy, cold, snowy weather, not to mention the lack of daylight. Did I comment on the snowy weather? And the lack of daylight? Seriously, I dont think anybody in their right mind tries this before May. Its simply too hard on its own, without adding the impediment of having the weather gods all arrayed against you.
So once you get him to agree to a May start, then we can talk. My own feeling is that a good wireless phone and charger is more than adequate. Get him an Apple iPhone ($199 with contract)its cool and it has e-mail, maps, and GPS. He calls every day at 6 p.m. or you promise to hunt him down. You are Mom, he will listen.
Other advice: Buy a copy of Barbara Siegerts Bicycle Across America ($14), a good guide to this trek. Get him a BOB trailer ($329), which will work much better than using saddlebags (a.k.a. panniers). Make sure he has lights lots of lights. Otherwise, hes young and theres not much he cant endure. But have a one-way plane ticket stashed somewhere. Many a strong person has bailed on this effort.
Otherwise, let him go. Bicycle accidents actually are quite rare. This is safer than sending him cross-country in a Ford Mustang. But dear Lord, not in January!
The 2008-09 Winter Outside Buyers Guide is on newsstands now. Look for it online soon so you can get prepped for gift-giving seasoneven if everything you pick is for yourself!