For a trade ship, never compromise on the thrusters and power distributor. With D-class and only a size 6 PD, you'll be a sitting duck if you get interdicted or when a pirate turns up at an ouptost. Those things are OK for an explorer, but not a trader. You need about 350m/s boost and a good boost frequency to be reasonably safe, but the more the better.
Ditch the weapons. If you tried to use them, you'll get blown up in seconds.
Ditch the supercruise assist, which only slows you down, and change the docking computer to a standard one. The auto take off is a complete waste of time. It only slows you down.
Now you can go down to a 4A powerplant. Switch off the cargo hatch, which you will never have to use. Switch the shield booster off after fitting it and put it on a lower priority in the modules tab. As soon as you leave the station, put 4 pips to engines and 2 to shields, then switch off the power distributor and switch the shield booster back on. With no weapons, you'll never need to change the pips from that configuration. When you switch off the PD, it only locks access to the pips. The PD still distributes power to the capacitor. You won't have so much problem with heat when scooping with the PD and cargo hatch switched off.
Add a heatsink to break target lock if you get interdicted or if the pirate tries to get you at an outpost.
All that's assuming no engineering and no Guardian stuff.
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