You don't. It's part of the mechanic.
WRT your comment on multi-role ships, I think you misunderstand me - you can do it if you want, but it's a risk you don't need to take.
Weight, in the form of cargo in your case, makes your ship more sluggish if you don't have A-rated thrusters (and sometimes even if you do.) To bounty-hunt most effectively, you want a ship that's nimble, fast, has good shields and hits hard.
Dragging around 60t of goods reduces two of those four - speed and maneuverability - whle also adding to the potential cost of being toasted.
A multi-role vessel can be good at several roles, but it doesn't mean you necessarily have to do them all at the same time. Instead, I interpret it to meanthat it can do them all with minimised costs. If you want to switch from bounty-hunting to trade, you don't have to reconfigure the whole ship or buy a new one. The Viper is more effective in combat than the Cobra and a T6 is a better trader. I wouldn't go bounty-hunting in a T6 or trading in a Viper - I'd have to buy a whole new ship for that.