Most people that full time in there RV have the internet issue and what I have come to understand as the best solution for across the country is this:
Two Mifi units (hotspots) with unlimited plans, one with Verizon and one with AT&T. Between the two carriers, there is decent coverage ALMOST everywhere. It's costly but unless you have an older cell phone plan that allows you to use your phone (as one of the a hotspots) without limiting your data, that's about the best way to have a fast enough connection to stream or surf, upload and download at reasonable speeds.
Check out
Technomadia.com which is the best source for internet and mobile connectivity that I have found.