I keep thinking I should add my controversial (or, at least, rare) Star Wars opinion, and this is as good a place as any: Solely in the context of the original trilogy, discounting what was in deleted scenes, novelizations, and the prequel movies, it makes a lot more sense if Beru was Anakin's sister rather than Owen being Anakin's step-brother or, more improbably, Obi-Wan's brother. It explains why Luke has a different last name, and fits with Beru having fond memories of Anakin and Owen's being less warm ("He's got too much of his father in him." "That's what I'm afraid of.") regardless of whether or not they know any specifics beyond, "Anakin left the farm for space-adventure and never came home leaving behind an orphaned son."
In hindsight at least it may have been the better choice in terms of Beru's character . . . but Anakin having a sibling introduces complications. Even ignoring the PT et al; the force is supposedly strong in that family line, so why wasn't Beru also trained as a Jedi? I think even Lucas struggled with this since he clearly wanted them to be family and have known Anakin, but not
too close a part of the family that it'd be implausible that they'd avoid being pulled into the whole Jedi thing, or why they're out running a dust farm in the middle of nowhere. Not that these thing's can't be explained, but it raises questions that the movie doesn't really have room to answer, so best to keep it simple and vague. Honestly, Obi-Wan having a brother seems much less problematic than Anakin having a sister given the generational distance and the obvious implied animosity between the two men (on Owens part at least, if not Ben's.)
So I'll do you one better that has all of the benefits you mentioned, and none of the complications: What if Beru was Padme's sister instead? No need for force sensitivity to be addressed, no need to worry about surnames, and has just the right amount of distance for a close relative that isn't
too close.
As for Luke's last name; I'm hardly the first person to mention this (indeed I think I've already brought it up before more than once over the years) but we don't actually know whether Luke always went by Skywalker growing up, or if that's something he took on after leaving Tatooine behind.
Mark Hamill has often told the anecdote of filming the detention centre scene, and first discovering his character's name was Luke
Skywalker from reading his sides for the day. Up until this point (basically all of the location shooting in Tunisia, and almost all of the stage work save the Yavin temple stuff) he'd been under the understanding that his name was Luke
Starkiller, since that's what it was in the earlier draft he'd read during casting, and wasn't changed until just a few weeks prior.
This is just me but I think it's a neat bit of head canon to imagine that moment is also the first time Luke ever said that name out loud. Thematically, that really is when he ceases to be Luke the farm boy and becomes "Luke Skywalker" the heroic figure. I guess if you want to add plot logic to it too; Luke
Lars would have been a wanted man at that point, so going by a different name is just prudent.