It would be pretty rare for you to need anything smaller than a 4.6m race/speed sail. At your weight you would probably be fine is it is a 4.6m wave sail as well. If we do get one of those rare, epic days of 40 knots plus you may need a smaller sail but if it's like that the size of the sail is only one of the issues.

At 75k I use a 4.4m sail as my smallest but I have a 3.7m wave sail just in case and I have pushing for a Custom 4m Koncept just for those rare epic days (without any joy so far :-)