I do not think this is usefull because cargo space is useless on the UI compared to the fuel and supply.
Because you need just to hit the "I" inventory shortcut for know your cargo space is also the reason why i do not see that usefull to put.
If this is not always 100% usefull like the fuel or the supply, so this is not important to put on the primary UI.
The rare case where i see that good to have, this is after defeated a huge fleet and have your cargo space fill, where you wait than supply is consumed for put the rest of the loot on your cargo space. But here, this is just when you begin the game, else, on the end-game, you put on a trashcan, the useless stuff.