I probably drive mine less than you H. Mine rarely comes out of the garage nowadays but I still wouldn't consider selling it.
When I do take it out it just makes it all the more special. It HAS to be manual for me though, like yourself I just don't enjoy the auto experience. If I was using my Supra as an everyday car the Auto box would probably be a luxury. But for when you just want to go out for a wee run, nothing beats the 6spd IMO.
You need to have the mindframe that the Supra isn't really your car, it's your toy. If you can live with that then I see no reason to sell. Obviously you need something sensible for the mundane but there must be a compromise somewhere surely?