Here are some rules I put together for running a seasonal league campaign. It's based on the campaign system I use for the Unofficial X-Wing Galactic Campaign. Its primary purpose is to establish an ending point to a league season, while providing an overarching strategy for league play and a variety of scenarios for players to participate in.
Note that this is not a narrative campaign consisting of a series of battles linked by a story; it does not have rules for hyperspace travel, permanent character death, resource management, etc. It does have room for league organizers to implement their own campaign rules using those elements if they wish, but those sorts of things are not integral or required to play.
X-Wing League Campaign PDF
http://www.outworld-studio.com/xwing/pdf/League-Campaign.pdf