This is how the tri tip was cooked at Oscar and Monica's wedding rehearsal dinner for 50 people:

 

Rub tri tip all over with Tones Canadian Teak Seasoning.  Cook meat in oven for 1 hour at 400 degrees or BBQ it. (Don't overcook it). Then set meat right into a cooler and it continues to cook some and stays hot for a long time.  Putting the meat in the cooler allows you to get the meat ready ahead of time.

Baked potatoes also keep hot well in another cooler.