Wow, awesome. Congrats on figuring this out, Al!
Just for fun:
The maximum available +17 to combat chance for the charnel house (with an air filter, without reading any disturbing canvases) would put 20 ghoul combats and 4 other encounters in the fray, allowing you to fight ghouls 83% of the time (and since one encounter is skippable, it's actually 86% of your Energy spent).
On the other hand, if you want to get disturbing canvases, the maximum +8 to noncombats would put 9 Stained Canvas encounters, 1 skippable, and 3 others in the pool, letting you get a disturbing canvas out of 74% of your Energy spent. (You could also try for a canvas in Garbage, but I don't know if the drops are complete on the wiki, or if the drops are equally likely).
Powerful stuff, in short, although the above scenarios would take a lot of effort and limited time effects.
In the beginning, men were mortal.