This is where common sense should be used. Come up with a maximum number of fans that can watch a game and observe the games to make sure that limit isn't exceeded. I suspect 99.5% of the games in baseball and softball will not approach the limit. If they do, then come up with a ticketing system. Otherwise, let the games go on as usual and don't deny people the right to see their school play.
I saw this over enforcement in the Fall and Winter. Same gym was used for all HS/MS volleyball and basketball games. A varsity game could have upwards of 150 people at the game. When the Middle School played there, people were turned away but the crowd never exceeded 40 people. It was the same gym...