Add automatic locks to 2005 Toyota Tundra

Well, one thing that bugs me about my new Tundra is that it does not automatically lock when you put it into drive (has option to lock when started though) Any way to make it automatically lock when shifted out of park, and automatically unlock when put in park? My though was to rig something up where is would "know" what state the locks are in, and have the trigger be the park indicator light on the dash, lets say the locks are locked, if the park indicator lit up, they would unlock, and the reverse if they are not locked. Any ideas?? I would think it would be really simple.

I was also thinking I could use a PAC TR7 somehow, but heres the problem. If I hooked it up to unlock the doors when put back into park, I need it somehow ignore the signal when the truck is first started (I don't need it to try to unlock the doors when the truck is first started, I only need it to unlock the doors when put BACK IN park after the doors have been locked automatically.) Hope this all makes sense