Study the graph below (created by jumpjack) to get an idea of what you might optimally be able to do. Takes self-discipline to always featherfoot and travel well below the speed limit for the entire trip. It's nice that you can travel the side roads and not the Interstate.
When making extended trips with the i-MiEV, you need to do your homework and have a Plan B and Plan C up your sleeve. Even though I personally think I could do it on one charge (given a large enough wager), no way would I undertake this trip without having sussed out all charging stations (public and private), RV resorts, and welding shops along the way, and verified the weather (especially wind speed and direction) before leaving. A bagful of adapters might prove indispensable. What did you say is your present battery capacity?
The good news is that this is also farm country, and most farms have a welding shop setup so you can get 240vac fairly easily. Hey, if all else fails, plan on spending a half-day somewhere on a 120vac outlet.
Be sure to peruse this Range-Efficiency-Operating Cost subforum for some hypermiling ideas; for example,http://myimiev.com/forum/viewtopic.php?f=28&t=287
To demonstrate your hypermiling skills and gather confidence in your abilities, how about posting a photo of your full-charge RR>90.