Is a Low-STR Blood Corsair viable?

The difference between MoN and HTP is negligible. One has 300hp, the other has 250def, which turns out, blocks about 300 damage.

I'd just use MoN though, because it's much stronger than HTP with the +10-12 attack.

But HB doesn't multiply DEF

Anyway, you're far better off maker'ing/ scrolling yourself some HP equips than doing this. That way you'll only have the damage loss at bosses, not all the time. And you honestly don't need the HP as much as a NL or a BM will, since we already get a fair it more than them.