Ah, so you want to offer all at the same time? I had assumed it's in a snake pick order for some reason. But yeah that would take too long. You could do it in groups. First 5 each get 3+3 choices for either civ or leader, then the next group and so forth. First group to choose has to makes the second choice last.
Offering every one 1 + 2 with 2 rejects should work too.
Offering every one 1 + 2 with 2 rejects should work too.