I never thought about mounting it back further than the dash... hrm. I wonder if you could try the dome light or something (depends on the car, also maybe depends on if you're insistent on charging it while driving since video sucks up the juice). The back window is also an interesting thought, but never tried it or crossed my mind. Would you want to see the dashboard for the speed or something else? That "DailyRoads Voyager" in the shot records GPS position and approx. speed, if that helps.
My suction cup used to fall down quite a lot when I tried mounting it on the dash itself with the little "mount" provided with the car dock, but it's stayed in this position for about a month and half now so far, in some high temps with the car outside unshaded (90+ outside). My case is a QMadix Gel off Amazon.com. It will fit in the default car dock yes once you remove the (removable) insert. It will not charge in the dock by default however... I had to modify my dock in order to get it to charge while in the dock. I was going to post something on my blog on how I did this modification, haven't done that yet though!