Biased as I may be towards certain models and brands, I do have a possibly relevant suggestion for a number of technical reasons.
That being said, I'm wondering if something with a slimmer-at-the-nut neck with a tighter fretboard radius might suit you. Specifically, a Fender Aerodyne Jazz. Here's some differences and similarities it has to your P-Bass;
Width at the nut: 1.5" vs. 1.625"
Fretboard radius: 7.5" vs 9.5"
Weight: 8.5 lbs.
Pickups: Precision/Jass combo configuration (you can get your familiar P-tone or literally "Jazz it up"…in other words, a nice variety of tones)
Here's a good sound demo; http://www.youtube.com/watch?v=UE076ensK8Y
A new one would be out of your price range, but I've seen used ones go for $450. But all that aside, if you can get access to one to try out, see how it feels first. Some people are a little thrown off by the physical differences between it and most other basses. To your hands, it may or may not be a good fit.