Stephanie,
Don't know if you are still reading these comments, but I see that you did mention the model, and earlier I has brought up gearing, from my experience riding heavy touring bikes in mountains.
The trek you are interested in does in fact have excellent mountain bike gearing, a 15 tooth front gear, and a rear cassette 10 speed of 11-42, giving very very low gearing, remarkedly low gearing.
They state it weighs 50lbs naked, so if you carried only clothes, and your husband takes all his stuff plus the heavy stuff, you'd realistically still be on a 65lb bike--- for sections where you have to push walking.
I figure to be realistic, you guys need to look at the route and figure out perhaps doing a less technical section, as well as being realistic about charging possibilities and how it is to ride of the battery runs down.
There is lots of divide route detailed info out there, but electricity access won't be mentioned that much, other than distances from trail to towns, and I can't imagine one can sleep in hotels every night in towns, but research will show this.
Cheers
you're forgetting about the planetary gear built into the electric drive unit itself. every time the cranks go around once, the drive sprocket goes around 2.5 times.