Four couples, unknown to each other, but screened as you say for basic body type, and for impressive verbal skills.
They meet at a restaurant.
Four tables for two.
They split up, sitting a man and woman at each table but not matched with their own spouses.
The man speaks first. For three uninterrupted minutes, he speaks to the woman. He may talk only about what he wants the two of them to do. He may discuss the sex they are to have, or whatever he wants of her. She may not speak. He may not stop. He may not ask questions about her. Three minutes pass, and it’s her turn. When they’re even, it’s his turn to ask questions of her for three minutes, which must be about sex and which must be of an uplifting type, rather than calling for bad memories and the like. Then it’s her turn to ask him questions.
The men then move one table left, and the pattern repeats. 12 minutes a table, figure just over an hour to do all four cycles with stopping to order food, eat, etc.
Somewhere in there, you’d find your own spouse for 12 minutes, catch up on what you’ve heard, but forced to do so within the structure.
At the end, the couples adjourn to a hotel room, and play a similar game:
Unmarried pairs. Two minutes to make out. Switch. Etc. There’s eight minutes gone. Everyone’s keyed up now, so next round they pair up as they first did at the restaurant. Three minutes to do something you talked about, asked about, discussed. Switch. Etc.
Twenty minutes in, the rules and the pairs are discarded, and let the wild rumpus begin.