Place your characters armor unlocks into the campaign cutscenes, just like in the days of halo reach.
It wouldnt have worked in halo 4, due to master Chiefs armor being so iconic to the series. However, now that we have Spartan Locke, who literally no one gives two -Yoink!- about, at least let his character be the representation of your characters multiplayer armor. There are too many franchises today allowing players to do this for 343 to not jump on the band wagon. Just a thought though! It’s something I’d like to see.