Feeding Everyone Outdoors

Outdoor catering fails for logistical reasons, almost never culinary ones. The food is rarely the problem.
The Kitchen Is the Whole Job
A caterer working from a field needs level ground, water, waste, power and shelter, and the quality of what reaches the table is set by whether they have those things. Couples spend months on menu tastings and ten minutes on where the kitchen tent goes.
Ask the caterer to visit the site rather than look at photographs. The good ones insist on it and the ones who do not are the ones who turn up short of a generator.
Service Style Changes Everything
Plated service outdoors needs roughly one staff member per ten guests and a great deal of covered space. Sharing platters need almost half that and land hot far more reliably. Buffets are cheapest and slowest, and a hundred people queueing in a field in the sun is its own small disaster unless you run two lines.
Family-style sharing is the format that most consistently works in a marquee. It is also the one that suits long tables, which you probably already have.
The Gaps Nobody Plans
There is always ninety minutes between the ceremony and the food where people have nothing to do and are drinking on an empty stomach. Something substantial in that window prevents most of the problems that occur later in the evening.
And late food matters more outdoors, because people are colder than they would be indoors and have been drinking longer. Something hot at ten o'clock is worth more than an extra course at dinner.