A major issue you'd have with that is cooking steaks to different donenesses. You'd quickly lose a lot of the benefits taking a med-rare steak to med or med-well, but of course, the people getting their steal med-well probably don't appreciate the differences anyway.
It'd be a much less labor intensive way to go.
You can use one of the standard sous vide cookers, like the Anova models, in very large containers if that container is an insulated cooler. If I was looking to make one for the type of of application you're talking about (making 20 steaks) I'd build my own. You could get a good 1200W element and connect it to whatever type vessel you'd like. If you wanted to get really crazy with it you could do a 30A 240V outlet and run a 5500W element.
It'd be a much less labor intensive way to go.
You can use one of the standard sous vide cookers, like the Anova models, in very large containers if that container is an insulated cooler. If I was looking to make one for the type of of application you're talking about (making 20 steaks) I'd build my own. You could get a good 1200W element and connect it to whatever type vessel you'd like. If you wanted to get really crazy with it you could do a 30A 240V outlet and run a 5500W element.