Last year we were issued 3 polo shirts and 3 PT shirts to use for the duration of SLE. We were unable to wash our clothes and pretty much had to bear through the sweat and stink on them. You will definitely wear each shirt at least once.
Less on the shirts, but I encourage you to bring multiple exercise(athletic) shorts, and khakis (long and/or short). Last year I made the mistake of only bringing 3 pairs of athletic shorts, two of which had "Navy" written on them(I guess you can already tell that I was called out a lot), so my clothes were stinky/sweaty during SLE. It also didn't help that the weather was hot and super-humid the entire week.