How to cook tubular ground beef using only disposable items?
You can try going with the classic Boy Scout "hobo" stew.  Put your beef, some sliced potatoes, carrots, celery into a foil that you then fold up completely to make a "poche" or pocket.  In this case the potatoes will absorb some of the grease...you'll still have the flavor.  But you are still going to have a lot of fat, such is the nature of 80/20 beef.

And, of course you could just broil burgers.

You might want to modify your question to state why you want to avoid using any containers.  If it is just a cleaning issue, you can line anything with foil and make clean up easy without having to go to so much trouble to come up with something.