How about use the PI Camera module instead? No wireless mess and much cheaper than a GoPro. I'm not even sure the GoPro video stream is accessible outside their proprietary app.

There are a lot of tutorials online on developing computer vision with the PI.

However, it sounds like the K.I.S.S. solution for you would be a backup camera or something so you can see whats happening behind you instead of relying on CV (computer vision) especially if you don't have the software chops to take on the CV challenge.