Hey Brad,
If time is not yet a factor for delivery I would start over.
I would suggest downloading the GoPro Studio software. It is available for free on the GoPro website. This software will allow you to transcode the footage from MP4 to the GoPro Cineform codec. The reason for doing this is that, while premiere is a very smart program and will accept almost any type of file, the MP4 is a highly compressed file type and there will be a loss of quality if you try to edit with it. The Cineform codec is basically designed to be used for editing. Depending on the capture settings, I’ve seen this software turn a 500MB file into something that is over 10GB.
Additionally, the GoPro Studio software can also be used for light editing, setting in and out points, color correcting and even filter application. (There is a Pro-Tune filter which I am very curious to see how it would affect your video) … It can also help with Timelapses / fisheye adjustment / anything gopro related etc etc
GoPro Studio Sofftware – https://shop.gopro.com/softwareandapp/gopro-studio/GoPro-Studio.html
If for some reason you are unable to download that software I would suggest using a different program to transcode all of the files to the “Apple ProRes 422 (HQ)” codec. Doing this will allow you to edit with one of the biggest file types, giving you the best possible video quality.
Good Luck!
And please keep me updated, I want to know how this turns out.
– Rob Pilgrim