Sounds good. First time you fill it up take it inside, download all the clips from it, dump it in a VLC player playlist and see what the total runtime is, then you'll have an idea if you drive a total of 2 hours each day to/from work, approx how many days you can get before you need to format it
What I did for the headrest mount was get a piece of plastic bar about 2ft long (not sure if you can get it at CT or HD, I got it from my metal supply place, Metal Supermarkets, was 1" wide and 1/4" thick, 2ft long). I pulled the headrest out, used the "legs" to mark holes on the plastic towards one end of it, drilled it out. I then put the legs of the headrest through it, then reinstalled back on seat, voila, super nice solid mount with no modifications to the vehicle. I then drilled a 1/4" hole through the part of plastic that was now sticking over the right edge of the seat and used a GoPro tripod adapter (linked above) and a 1/2" long 1/4" bolt and just bolted the tripod adapter to the plastic bar. Worked perfect, could use my Drift, Contour (after converting it as explained above) and of course GoPro.