once you get to friendly with a faction those cargo scans almost never happen to you if there is anyone else nearby they could go after instead. At cooperative level i've yet to be scanned by a patrol, they just assume i'm not carrying anything illegal.
But until you get to that point i'd say don't always make it a point to carry cargo, even if you go 100% trading, keep your valuables and your commodities under lock and key in a station's storage facilities, its a one time payment of 5,000 credits per station and once you start collecting some bounties ( you said your going for a mix of combat and trading) this shouldn't be a problem. Then only take your commodities out when you know where it needs to go, for example you've been stockpiling food on Jengala in the corvus system, and suddenly you get word that there is a food shortage on Asharu, you quickly rush over to your food supply and ship it all over at once ( or in a few trips if you can't carry it all) and bam, all the credits and rep, plus quite a bit of XP for the massive trade. If you move relatively quickly its unlikely a patrol would have the time to scan you before you take off and get under way. And if you have to you can try to evade the patrol because getting caught with your cargohold completely full is not a good idea even if you aren't carrying anything illegal.
And for the record i've always thought the inspections are quite harsh especially to brand new players, just the other day i started a new game ( im not anywhere remotely new to this game) and within minutes of the game starting i was being pinged by a patrol. quite harsh to immediately lose a chunk of my starting credits, and to a less experienced player that blow would cripple them.
I've also always been against the huge fines for carrying legal goods, illegal goods i can understand but for goods that are perfectly legal that's like a cop pulling you over for driving a car that just so happens to look like one that was stolen earlier that day and when he determines you didn't steal it he arrests you anyway, honestly that makes no sense to me. I realize people are going to retort with, well the patrols are clearly corrupt and they have quotas to fulfill, and I call Bull- **** there is no way that every single officer of ANY faction is completely corrupt i'd bet even some pirates would find that.. distasteful, they'd rather take your money by killing you first. ( a more apt metaphor would be a cop pulling you over under suspicion of having alcohol in your car because you have a brown paper bag in your passenger seat, and when he pulls you over he finds out it's your lunch for work then arresting you for a DUI anyway)
( and by the way I censored myself, i'm well aware of this forum's rules about cursing, even though I swear like a sailor I will abide by the rules)
And to anyone who would argue that the fines aren't crippling for a new or less experienced player i have a friend who just redownloaded SS today after having been away from it for over a year, ( And even before that he hardly played it) and immediately he was scanned by a patrol too, and lost half of his money and had to start over because he couldn't afford to buy supplies and slowly died from one pirate fleet because his ship didn't have enough CR to keep fighting back.