If you just want to get the balance between the pickups that sounds good to you, rather than being able to adjust the blend on the fly, I would have thought that being able to adjust the heights of the pickups AND the pole pieces should allow you to get the balance you're after.
Having said that, I'd never want to dissuade anyone from whipping out their soldering iron and if you do decide to go for two volumes, I'd be interested to hear how it turns out.
The one mod which I did on my L2000 was to replace the 2 way series/parallel switch with a 3 way switch to give series/single coil/ parallel options. A really worthwhile mod IMO - it extends the tonal range of this versatile bass even further. In fact I use it in single coil mode most of the time.