Updating this to maybe help someone else.
My trans took a crap, so I was dealing with that.
Now that the trans issue appears fixed, I was able to verify the hot start issue is fixed.

I replaced the CCA (copper clad aluminium) wires with 00awg copper and that fixed the issue.
I now measure a 2V improvement in voltage drop when cranking the motor (9.5V vs 7.5V).

Not sure why it was only an issue when hot, but the pure copper wire works.
I guess there's a reason the CCA wire is 1/2 the price........