We've traveled much of the USA (East to West) including Alaska and have never been without a Verizon phone or MIFI 2200 signal. We've had weak signals but things worked. All be it slow but they did work. We have a Grandfathered unlimited 3G plan. Only time we turn devices off is traveling through Canada.
If and when we needed a signal and did not have one we would just go to a local hot spot. Not sure how that would work for someone running a business on the road but there are plenty of places providing internet connections.