Pickup coil width is a fascination to me! (I know, I know: get a life!).
I'd like a shortie stingray, but with a pickup that is smaller so all the relative dimensions are the same. I'd love to find out if I can hear a difference. With the usual pickup on a shortie the pickup is sensing a higher percentage of the string than on a 34 scale.
Aguilar and Nordy do thin Bart sized soapbars with separate lines of polepieces, although they are doubles and not the 1 large pole as on a 'ray pickup.
Maybe one day I'll get someone to make one... and then discover I can't hear the difference and I've wasted £500 on a custom pickup!