Here's an idea I had to reconcile Owen and Beru's statements about Luke's father with Kenobi's statements about Luke's father. What if Owen and Beru were referring to someone whom they thought was Luke's father but actually wasn't? My idea is that Owen had a brother, let's call him Grant Lars, who had starry-eyed idealism in stark contrast with his more down-to-earth brother. Grant was the one who served as a navigator on a spice freighter, the person Luke as referring to when he said so in response to Kenobi's talk about the Clone Wars.
So Grant was piloting a spice freighter when his ship was called into service as part of an auxiliary arm of the Republic Navy, similar to how the US Navy assigned merchant marine ships to serve as materiel and troop transports in World War Two. It is this incident that prompted Owen to say to Grant that he should have "stayed here and not gotten involved."
In keeping with my other recent thread "Anakin the Nameless", perhaps on one these cargo runs the young Force-sensitive sneaks on-board to evade Hutt cartel assassins. And then it is through Grant that Anakin meets up with Kenobi and a diplomat from the Organa family who will eventually be his wife. This also seems like a good opportunity to set up a love triangle between Anakin, Ms. Organa, and Grant Lars.
Just some wild speculation on my part, let me know what you all think!
Note: I just now realized after posting this that Grant Lars has the same initials as everybody's favorite ruiner of the Original Trilogy. Make of that what you will.