Help me make sense of my vehicle's towing capabilities

Well you’ve come to the right spot for advice that ranges from a mountain out of a mole hill to picking fly sht out of pepper.
Short answer is, one , it depends how you’re using it. Thousands of miles every year and difficult towing (mountain grades) or a few weekend warrior trips.
Either way, I’d be comfortable in either scenario up to right around the rating of the Caddy.
And yes a wdh does reduce the hitch tongue weight.