[Amp Mad Scientist]

I have a Fender CS Esquire and love it however miss not having a neck pickup. Noticed that pickups are generally sold in sets unless purchasing a high-end Ron Ellis PU or something similar.
So I’ll throw out this question. Will converting the Esquire to a dual pickup guitar work against me if I decide gown the road to sell it? The traveller sheet that came with it shows sgl bridge PU configuration however the guitar is 20+ years old. Your thoughts or experience. PS would purchase new vintage pickguard and keep the original.

If the modification is clean neat professional, it won't really hurt value.
Adding a neck PU is OK.
Now you need a PU switch, and you might want volume + tone controls.
Will you get back all the money you put into it? Probably not.