Just my .02 here...
Slimming the neck isn't too difficult, however changing the scale length is a different foxhunt altogether. Not impossible of course, but a lengthy and I would guess not un-expensive job, considering the fingerboard will have to be replaced, as well as the bridge and probably the tailpiece moved too. Might be worth doing if you found a bass in need of restoration, and didn't mind putting the $$$ into it. If you look long enough, you may even find a Europa that already has the extra-long scale, although it would likely be a multi-string. (5 or 6)
Regarding the TI's... I love 'em, but you're right - they're very soft tension. I like them that way... FWIW, I have them on a medium scale (32) Persuader 5-string, and find the tension to be much more to my liking than on a couple 35 scale instruments. YMMV of course.