Ok here's my next idea, part of which I'd forgotten about.
Obviously you already know my feelings about Hayden Christensen and that I think he should be recast with another Anakin but there's another reason for this as I believe it's prudent to completely get rid of Jake Lloyd and that we meet Anakin as a teenager of Luke's age.
He won't be a slave either and will be either living with his mother and brother or just his mother (if Owen is Obi Wan's brother instead). I'm struggling with the details of what point in the film Obi Wan will meet him, or whether they're actually stranded on the planet or not But there will be a race, and Anakin wins - whether there's anything at stake for our characters though, I don't know. I haven't thought about it enough.
One thing that will change though is it won't be podracers anymore. Driving a mechanical 'chariot' does not say 'pilot' to me, and Obi Wan says Anakin was already a great pilot when they met.
Instead, he's in some kind of (possibly illegal) race involving airborne ships, winding through beggar's canyon and his own particular ship is one of these:
Look familiar?
This way, Luke playing with the model of his T-16 becomes a nice little nod to the prequels without being too blatant. It's the kind of subtle touch I just love seeing in a film. Perhaps the one he has is still the same one left over from when his father left.
Anyway, whatever the circumstances of the race, it will occur when the sith have already returned and Obi Wan knows it and they need all the Jedi/pilots they can get. That way he can tell Anakin he has the force and ask him to come with him on his 'idealistic crusade'
Again, all this is probably impossible, but it's how I think it should have been.