That's not a bad idea if the heat will still come through.
I have a tendency to tingling fingers, probably from work-related nerve damage, and I don't like grips that are too fat as they seem to make it worse. And fat grips make the throttle action feel odd. Before I had it blue-printed, my Ducati used to set my fingers off. I bought some thick foam grips from Nippy Normans. They felt great at a standstill but made the throttle feel weirdly unresponsive when riding so I took them off.
Black leather wraps might work though.