There is no physical limit to the amount you can have in your cargo bar the actual size of your cargo hold, just the amount you can locally purchase.
Imagine the hoo-har if RP pirates could only carry a small amount of goods which have been donated.
RP: Yarrr. What are you carrying. I want it all.
Trader: Oh, hello sir, I am carrying 5 tonnes of Sothis Gold. Please don't shoot, you can have it all....
RP: Yarr.... Jimmy boy, check the cargo hold, can we take that?
Jimmy: [Scared to reply] errr. err, no sir, we already have 6 tonnes. Can't carry anymore in out 192 tonne iClipper.
RP: Yarrrr.






, Jimmy me lad, get me Fang on the blower, I need advice.....
Also, please bare in mind that a live, Ed Lewis stream actively demonstrated and with ED staff, took part inthe above method of loading up.
I do believe that is your answer regarding the exploit.
Now, should I stop giving all CMDRs I see my 20 tonnes to added to their 20 tonnes at Frost dock?
#ForTheMug