[Callers] Floor Space Requirement

Friends, I have been hire to call a wedding with 145 attendees and 15 known contra dancers. The bride and groom are insisting on modern contras. I have never thought about floor space, what is the typical requirement for a line of twenty couples? Any very easy duple improper dances to recommend? I plan on using "Family Contra" and "Jefferson and Lincoln". Thanls, Rich