Instead of setting a page for the item to appear on, put a script on the page that conditionally inserts the appropriate item into the inventory. For instance, if the %GENDER for a male is 1, the shorts item's ID is 1, and the skirt item's ID is 2, you could have something like:
IF %GENDER := 1 THEN $ITEMSTATE1 := 1 ELSE $ITEMSTATE2 := 1