Yes. One 18 quart roaster is just right for this size recipe. I would do a recipe using 6 pounds of pasta, since there will be some adults there also.
Make the recipe all the way to baking as usual. Coat the roaster cooking pan with non-stick spray and a coating of the grated Parmesan cheese. Preheat the roaster before inserting the pan, at least 20 minutes covered.
Use the guidelines on the spaghetti page for baking large lasagnas, it explains the difference in timing for freshly made versus made day before and refrigerated versus frozen for baking.