I think I'll just (save and) buy a 5-string bass since I will be sticking to B tuning for a long time and I want the notes to be heard and minimum fretbuzzing and clanking.

Still lots of bands like Carcass, for example used to downtune their 4-string bass guitars to B. Or even Mortician's Will Rahmer tunes his bass even lower than B. The result of course sounds like a coffee machine gone wrong hehe but if he's happy what the hell. I think he still uses a 4-string, not sure. If he does, he could at least get a 5-string bass and downtune that!