That's a good design idea! And yes - benches are good to have, even if it would be 99.9% of time one sitting alone at the fire.

Twice a year I remove the stones to clean out the layer of ashes, and then re-arrange the stones. Using and old truck rim sounds handy and clever. I think I'll need a more permanent summer kitchen, with a roof to protect from rain. Let's see if I get one built for the coming summer =)