What I believe could be done is for the spaceports to sell the equivalent of cargo racks to CMNDRS. They could be of different sizes just like cargo racks for ships and have the ability to store at least the following items:
Commodities
Weapons modules
Materials of all kinds
Data
You could buy 8, 16, 32, 64, 128 ton size and data/mat size same as within ships as an example. I would pay 500,000 CR for a 64T/8 weapons module/600 mat/200 data storage unit. This would really add some flexibility. These modules could be bought and sold just like cargo racks.
For example, I mine with my Python, but I need all weapon modules for armament at times. If I sell off a moded weapon for a mining laser, what happens to that mod, particularly a mod grade 5 that wasn't easy to achieve? AFAIK you lose it. It would certainly add to the Engineer part of it. They could also add mats and material loss if you are destroyed, it would be on the CMNDR to safeguard ship contents. Also, this opens up valuable cargo space for the smaller ships where space is premium. It would also allow you to travel empty and not be subject to cargo interdictions.
"Starship Troopers"
Robert Heinlein