With 30 units on a side you could accommodate 3 players on a side. For such large battles you could use the quick play large battle rules developed for Blenheim 2004. They are on the
www.warflag.com website. Just look down the right hand side and click Blenheim 2004. At the bottom of the Blenheim 2004 page there is a link to click to get to the free download rules, as a ZIP file, complete with charts.