I'm not sure exactly what I did, since I lost the schematic, but in the 80s I modified my strat so that the second tone control does weird things to each position except the middle. In positions 1 and 5, it adds in the opposite pickup (1+3 or 3+1) and in positions 2 and 4, it sounds like it does something to add another pickup out of polarity, so the tone gets thin and kind of English horney or oboey respectively. Essentially, each position gets to be more like itself. Weirdly, the 1+3 and 3+1 sound different, so I'm not sure what's going on there. The fact that it's on a pot instead of a switch is very cool because you can dial in the amount to taste and quickly back it off if needed.
I wish I could find the article in Guitar Player I took it out of, but it was too many decades ago.