OK, I've found dozens like this
. They're used on ATV winches for the reversing DC motors. But they're not rated for AC. Might work, but I'd want to see it in writing.
Then there's this
one. It's got a 12V coil and it looks like it's rated for 30A at 240VAC. So in theory it would work, although it looks a little small to me. Not sure I'd want to push 30A (or even the 20A I need) through those small spade connectors.
And the big industrial ones seem overkill, and as you said don't typically come with 12VDC coils.