Can you share what you did to remove the pinstripes? Since you did it to both sides I'm guessing there was no damage to the underlying paint or clearcoat.
That GX retrofit on the thread you linked didn't even work out in the end despite a ton of work. If you can't even make a GX heated steering wheel work on a same generation GX then it sounds like more trouble than it's worth to try to make it work on a 100.
I wonder if a heating element can be...
Agreed, that looks expensive for what it is. Best feature appears to be that it's a 2007, but has some minor maintenance issues and no mention of timing belt or water pump. Could spend just a little more and get a 2008.