I will preface this by saying I am not a modder, and don't know if this is even possible within this game.
I have a collection of mechs I have no real use for other than "I kinda wanted to keep this" and was thinking it would be amazing if we had a spot we could buy a base, be it the starter tutorial base refurbished or a spot at a certain Merc Star.

Have a partitioned "Mechbay" to store and display some of the hero or trophy Mechs.