I love this idea!
+1 to this. As it stands, I really struggle enjoying playing vanilla. When you deploy on any map that doesn't involve objectives, you're pretty much dumped right on top of the enemy. And your carriers may randomly decide they'd like to go in front of the battleships during the deployment, so that they can taste the vacuum of space and become a nice debris field the battleships have to wade through to fight the enemy. At least with Realistic Combat mod, the battle map is so large that I've got time to re-adjust the battle lines before the enemy reaches me. The only way in vanilla around this is deploying a frigate first, then sending in waves of reinforcements in the order you want them appearing on your battle lines.
Mount & Blade bannerlord realized the need for this...you can put your infantry in front of your archers and put cavalry on your flanks, like any intelligent army commander would do. Why can't I arrange my armored battleships up front, slow aluminum carriers safely behind, and nimble frigates and destroyers protecting my flanks like a smart fleet admiral would? (frigates coming in from the sides doesn't count, they're so far up they're of no help protecting your own flank)