If you are fortunate enough to have a large lasagna pan, place it over two burners. Make the gravy with cornstarch as the thickener rather than messing with a roux. It's too difficult to determine the measurements you would need if you make a roux. Plus, by thickening with cornstarch, you won't have as much fat in the gravy.
The advantage of cornstarch is that you don't have to pour the broth into the thickener. Instead, once the broth is lightly boiling, you add the cornstarch slurry. If it's not thick enough, add more slurry and stir. By adding the slurry a little at a time, you will get a perfect texture.
Excellent results can be had by using pre-made stock, in whatever flavor you require for the meal. I would add tumeric for color and flavor if making a poultry flavored gravy. There is a wonderful flavoring called "Washington's Deep Brown Sauce" that gives beef gravies an amazing flavor.
To store, wash out plastic gallon-sized milk cartons, and fill with the help of a funnel (cheap plastic funnels can be found at Wal-Mart and such stores). Cap 'em, and refridgerate. Pour into microwave safe bowls and reheat as needed on site. If you have to, bring your home microwave with you.
Season of course with salt, pepper, and whatever else you like in your gravy.
This is easier than it sounds, and like Crewsk with her smoked turkeys, you can handle this one without breaking a sweat.
Seeeeeya; Goodweed of the North