[Baron Munchausen]

It's messy, but there is a way to arrange something like this. Formations will accept ship 'names' as well as classes, much like the build queue. So, you could make a formation with 'light attack ships' assigned to the front row, and 'heavy attack ships' assigned to the back row, and 'missile ships' assigned to the rear. Then make sure to put the right numbers of the right types of ships into the fleet and they should be assigned as requested.