Bartolini "classic bass" soapbar pickup in "sweet spot" position?

[tubby.twins]

Hi,

Has anyone used one of the Bartolini "classic bass" pickups in the "sweet spot" position, i.e. mounted between where the neck and bridge pickups would normally go?

If so, did you choose the "neck" or "bridge" models? Which of these two would you recommend?

I currently have a Warmoth Gecko 5-string fretless bass, with a pair of Bartolini P25CBC pickups in the usual neck and bridge positions. Each pickup sounds good when solo'd, but using both pickups together produces a tone that I quite frankly don't like. It lacks a lot of midrange detail and warmth, and sounds empty and flat to me.

So I am thinking of using a router to carve out a third pickup cavity between the existing neck and bridge pickup cavities. (I've done this before on another Gecko bass and it worked fine; there is enough space for a third pickup cavity.) But I'm trying to figure out whether I should put in a "neck" or "bridge" model in this new "sweet spot" position. Ideally I'd like to get a nice singing fretless tone from this pickup position as well, with the rich midrange and detail but still adequate fundamentals.

Any advice or tips would be appreciated. Thanks!