Unless anyone else has actually tried this on here, I've got a feeling this might be a question for Tim at BKP.
You'll like the Yardbirds, and I think a Mother's Milk would fit in nice with them. But what happens over the pole-pieces and wotnot, I've no idea!
(And I have to admit, I've been tempted by the tones, but an additional strat pickup just don't look quite right to me either :lol:)
I think I've heard of some people going for two tele neck pickups? If you like the idea of that look, when you get the Yardbird neck, you'll find it's really sweet and clear, and it might actually be a candidate for middle pickup duties? Another possibility would be the Blackguard neck, which lots of people say sounds very stratty... something else to think about maybe?
And welcome to the forum :D