What mat size do you need to run a club with 10-15 people in it? Is 20' by 20' enough or will it be cramped? Also I cannot seem to find a review of Zebra 1 and 5/8' grappling puzzle mats anywhere. Anyone know how these are for take downs and throwing? Yes it would probably be over a concrete floor, but we might be able to get a wood floor. Would that make a big difference?