I suggest putting a clone of Luke in a tank on Exogol. That would imply the Luke we saw in TLJ was actually a deranged clone - maybe Luuke from the Thrawn Trilogy survived and tried to train some Jedi.
Something to suggest Palpatine is a deranged clone would be nice as well.
For a bonus: maybe the Star Destroyer fleet was created by a Star Forge from KOTOR. Put in a shot of the Star Forge or a reference to it into the film and it could provide some explanation for that nonsense.