(I am not an AAA game developer so take everything I say about graphics with a pinch of salt.)
Mags in NGS are essentially just cosmetic pieces. Aside from scanning certain objects they serve no functional purpose. Why not go all the way and make them something you can customise?
With a game centered around fashion, having extra cosmetic options would only be a benefit to players.
With NGS bumping up the detail of the character models I doubt the game would suffer from it, but there should be a smaller accessory limit, due to them being less detailed than a player model. As a rough idea, 4 accessory slots and 9 accessory points. Just enough for a couple small accessories or enough for one "big" accessory (i.e. D'Or Veil).
To add accessories to a Mag, you would go the Salon and select a separate menu to edit your current Mag, much as you would edit your Auxiliary in PSO2
(Quick mockup of adding accessories to a mag)
On top of this I'd suggest having an option to display other player's Mag accessories that's disabled by default on lower settings. In lobbies it wouldn't pose much of a problem for lower-end systems since a player can only see their Mag, but it might pose a problem in exploration zones that can display up to 32 Mags at a time.
One potential problem I see is the anchoring points of accessories, due to Mag models being radically different in comparison to a player model. I am unaware of the rigging or the animation data of Mags so I don't know if it would be feasible to manually add the anchor points a player model has to every single Mag. I'd suggest having all accessories anchor to the center point of a Mag by default and have the player adjust them as needed.
(Mockups of possible uses.)
Is this something you'd be interested in?