No need for a lower cooking surface, just toss your steaks on the coals to finish them off. I think @bgebrent posted some r.s. caveman steaks the other day.

+1 on caveman.

I typically fan the coals lightly to remove any accumulated ash. And you want nice hot, cherry red lump for this.

Another option, if you don't want to caveman it, is to get a small cast iron grate and just lay it on the lump. This will give you a buffer from the lump, but still give you a sear.

What @ColtsFan said if you don't want to lay them directly on the coals.

I have used these grates for that and to stretch over an open fire. They are cheap and can come apart if you need separate pieces rather than one long piece:

This^^^