if you use mywi and a wifi only iPad you can use the Maps to show navigation routes?
Depends -
As you know, 3G iPad uses A-GPS which uses a database of cell-tower locations to get a very rough fix, which makes finding the real satellite fix much faster.
Wifi only iPad uses skyhook, which triangulates from a database of known wifi base station locations. This is very accurate if you're in a densely populated city with lots of wifi base stations around. Accuracy is through pings to three base stations and depending on how it takes to get a response from each triangulates your position. Work well but DOA in less populated area.
Based on that, I wouldn't count on the mifi - bouncing from spot to spot for accuracy.
I wish you all well in HI....I'm hearing there's a chance of strong wave from the earthquake heading your way.