Did this for years. Here are the results.
You want an antenna adapter for your EVDO card and a Wilson Trucker Antenna. This will bring a moderate signal to five bars.
Next step up, a good amp will bring a weak signal to five bars but it will not take "no signal" and make it into a good signal. Even if you have a portable 40' tower (been there done that)
you will not operate outside the timing boundary for the cell tower.
Summary, unless you are staying inside the people hive, you will need to have a motosat system and all the complexity, power draw, etc, that this involves.
Have fun.