I thought for sure Bob hit your problem right on the head.
I had a problem just like yours a few years back with hot starts.
I bought all new cables and 1,000 CCA battery.
And I still had problems with it starting after it warmed up.
I had cables going to the frame and engine block.
I had even used sanding paper where the cables connected
to the engine and frame. After being stranded for hours
with the thing several times. I went and got a short cable
and went from the cable on the engine block to the
starter bolt. After that all my problems went away.
Been starting right up for years now, with no problems.
Kurt