Looks like you're off to a start. Here are my comments...I'm no iphone fan or guru so I will do my best here.
- Doesn't the iphone have built in GPS? That may be less hardware you need.
- I would avoid the inverter. You may be good just to convert one of your cigarette lighter plugs into a USB port and use that if you need to charge. But I'm sure you wont need to plug it in all the time if your phone is charged.
- I don't know much about the mimics. I read mix reviews but its a cool concept nonetheless.
- I believe you also need to purchase and install the software to work with the mimics module.