The thing with militia though is that the game regenerates them for every battle, I think, so if you make too many, the militia will keep coming and coming.
By the time LR mod is done, Planetary Bombardment will be much more ineffecive(which is IMHO much more realistic) and Invading enemy worlds much more important.
And, as you may know, when I get more time on my hands, i am making a mod, accurately named Planetary Invasion which is SE on a planetary scale, with a emphasis on combat.