I did something similar on my car. The universal dash mounts put the phone to far away to be convenient and I cannot use the vent mounts because none of them fit my car. I already had a hard case and just used velcro tape to stick it to the dash. The black velcro tape blends into the dash pretty well so you don't really notice it when the phone isn't there. I only use the hard case to stick the phone on the dash or when I go skiing the the phone doesn't break when I crash.
The biggest problem I had was battery drain and recharging. I killed the battery in no time on one long road trip using garmin mobile for nav and modio.fm to stream some radio through my storm. When i tried to charge the phone it simply wouldn't take a charge. I tried charging it with the standard car charger, my wall charger hooked into a 12V DC to 115V AC converter, and using the usb cable and my laptop and none of them worked. The back had gotten pretty warm being insulated by the plastic case for hours of heavy use. I took the phone out of the case, let it cool down, and then it started to charge. There may some sort of overheating/overcharge protection that prevented my from charging the phone when it was warm.
I don't know if this has been posted I stopped reading at page 2. but...shouldn't you have used one of the tapes with the 3.5mm jack shortened the wire and you could have car audio?
