I need some video editing

We are looking to emulate a Head-up display for a vehicle. As part of a larger video presentation, we need help on a 20-30 second video edit portion.
We are looking to demonstrate what you see when driving a car with a rear mirror in the field of view.
The video will show the view from the driver's perspective negotiating a roundabout.
We have videoed both forward and rear-direction videos simultaneously - so you will utilise those two recorded video's.
Embedded into the rear view mirror will be a series of texts to show current speed and current gear together with a couple of symbols showing navigation and fuel warning.