To mount your GoPro camera, rigid is better. The plastic GoPro mount is ok for softly sprung cars but in high vibration environments it permits too much movement which can result in the rolling shutter effect that looks like a wave running through the video. By using a 1/4-20" tripod adapter on the camera, you can connect it to any standard mount such as I/O Port or the RaceCam that we sell:
To connect a Traqmate - GoPro Camera interface module, you will need to have access through the rear door of the polycarbonite camera housing. There is a template on our website to cut your own.
Before you can connect a microphone, you will need a GoPro camera housing with open sides. This is available from GoPro and is called the skeleton case. Obviously this compromises the waterproof nature of the camera. The skeleton case has the added benefit of allowing easy access to the SD card without opening the case.
For use in an open car, we recommend an external microphone be connected to the HERO2 camera. (HERO1 cannot accept external mic). This eliminates wind noise and allows you to tailor the sound to exactly what you want to hear. There are a number of mics available. We used this one and got acceptable but not stellar results. If you choose the Sony microphone, beware, there are counterfeit versions of it online.
To connect the microphone, we recommend a right-angle 3.5mm stereo extension cable. This allows you to dress the wiring behind the camera and lowers wind drag.
Here are some photos of one of our installations. Note how the wires are secured by cable ties so that the weight of the cable is not pulling on the connector which can cause it to become loose over time. For a rain race, the wires can be taped off and the skeleton housing can be swapped with a waterproof housing.