@jimb0
Yes, it's true about the added moisture - and that was the aim of my tinkering, of course. Next time, I'll see which pan it is that has the sinker. They're almost identical pans: same color, same thickness, same depth. Cooked on the same rack, side by side.
Maybe I'll drain the carrot/coconut/raisins more fully after their soak next time. Or leave out the mayo. It's just that I love the current texture so much, lol.
The original recipe also calls for the cakes to be baked in 3 9" pans, but IMHO there isn't enough batter - or rather, they would be much thinner layers. Do you suppose that's making a difference, too?