There is no great solution for an oven on the stovetop, even stovetop ovens aren't that great. The two are entirely different styles of cooking. The only thing I can think of that comes close is a dutch oven as the thick sides conduct more heat around the vessel, but that still gets most heat on the bottom.
If you want to do a lot of browning of the tops of things in a commercial situation then you could invest in a dedicated top grill unit, these are just for that purpose, a bit like a broiler except it's a table-top unit. If you want to brown the top of things and melt cheese every once and awhile but can't have an oven then I would introduce you to my good friend the piezo ignition gas torch which you can pick up in most hardware stores.
Other than the equipment side I'd suggest you modify your choice of dishes and ingredients to fit the equipment you have available. You can struggle trying to re-create oven cooking on a stovetop with mediocre results, or you can learn to make falling off the bone stovetop slow-cooked meats. One approach is more rewarding than the other.