Oh. Uh, yeah, for some of the late game thorium stuff I'm pretty sure I already mentioned I ended up cheating like goddamn. Slapped that thing in the face with a twelve inch cheat engine. Not so much the game's fault (... except for the very last boss or two, because good god) or even mine, just my computer and its inability to handle the performance requirements when the screen's lit up like a fireworks display of murder. Reeeeaaaal hard to survive a fight when it's a slideshow and your command input takes a second or two to notice you told it to do things

... that said, as mentioned there are a few things that can do some easement. Mentioned the throwing thing already... even if you can't scrounge up the max-hp damage of transient enemy existence, getting desert dude and the "yes I'd like to triple my damage" accessory can do wonders for dealing with stuff without getting gibbed. Could swear there's a couple other things like that, that can seriously make stuff easier for at least a bit.
Forget how I handled the abyssal, though. Pretty sure I didn't freeze my health for that one, but can't recall how I managed it...