I think another good option is an externally mounted 'lipstick/bullet/helmet' camera that can be used with any old camcorder that accepts video inputs. You can buy them online (ebay) for about $100-200.
I haven't tried it yet, but I like the otpion because it:
1. makes use of the old camcorder with a high recording capacity.
2. put the camera outside the windscreen.
3. is really small and has many mounting options.
4. since the camcorder is in the cockpit (while the bullet camera is outside) you can easily control it without remotes, etc.
5. cheap
The only snag is that your old camcorder has to accept video INPUT and many of the entry-level models don't.
Does anyone have any experience with this kind of setup?
Here are some examples (including a tail mounted perspective):
RV6 Video
Mounting Examples, etc.