Pizza food truck!

As someone with Celiac Disease (autoimmune disease where I get super sick from gluten) I would never eat anything out of a food truck. The limit for something to be labeled as gluten free officially is 20 parts per million. So if one crumb gets in my food, I’ll get sick.
Even with an appetizer table, the risk for cross contamination of gluten is pretty high. Also, I would be upset if I went to a wedding and all I could eat were the few appetizers while everyone else got a meal. I would probably leave early so I could go eat.
I would look in your area for restaurants that provide guaranteed gluten free food (prepared in a separate part of the kitchen with separate utensils). Do you have a California Pizza Kitchen near you? They can provide gluten free pizza that’s prepared separately. See if one of these places can deliver the food fresh (don’t want cold food).

Since it’s only 2-3 people, I think you’re fine with your initial pizza truck idea and then you can make small accommodations just for the select few.

I also had a food truck caterer (crepes) and have a friend with celiac disease. This became a serious conversation around the entire menu.

The caterer had one burner specifically for the gluten free and cooked that entree first. We also had a conversation about utensils and other sanitation. We also provided options for the entire day including a separate gluten free cake slice, two huge family-style side salads as well as appetizers. If you have anyone with celiac's, make sure that they have enough for a full meal and really critically discuss what they're cooking approach is to making the gluten free option.

If everything is made out of one oven, I would really hesitate to use them. There's no real way to prevent contamination.

I would bring in separate meals from a different place. That’s what we had to do for our kosher guests.