A baseplate is desined to give more low end and take away some of the harsh brightness a Strat bridge pickup usually has. The neck and middle positions don't have that problem so you don't need them and it could add a bit of mud to the sound of the neck pickup.
In your point a view :D
I would like a little more push to be a little like P90's :P
In that case, you might want to get your hands on an actual P90 or MQ, 'cause I think the size of the actual magnet, plus the different housing do something to the sound that added heat just can't touch. I find P90s to be both aesthetically and sonically pleasing :D
EDIT: I don't know if a muddy BKP is possible, I've had an MQ under some nasty, quite disgraceful distortion and it was still clear.