What if he turns and sees the image of Han, then he drops his saber and the scene continues. Then afterwards he has the Han memory scene.
Now that’s an idea… it wouldn’t interrupt the existing scenes too much, but still have that implication of Leia’s involvement. Combined with Leia’s body disappearing after Han disappears, I think that could maybe work. Of course, if Leia’s disappearance is moved up, that does mean any other scenes with Leia’s body need to still happen before the Han conversation begins.
FWIW: I think moving Leia’s body disappearing to immediately after reaching her son is a decent idea. I’ve never at all liked the idea that Leia effectively dies when her son does, but her corporeal body just lays under a sheet for the next half hour of the movie. It’s such a weird way to “pay homage” to Carrie Fisher and Princess Leia, by using the suggestion of her dead body as not much more than set dressing.
If her body disappears just before she distracts Ben, it removes that sort of distasteful use of the character from the film, AND it makes Maz’s explanation of what’s even happening with her a little more coherent - we literally see it take “all she has left” to do that.
If Leia disappears right after Kylo throws his saber, I’d be fine restoring Rey’s ‘Leia’ reaction because then the sheet dropping later does give the allusion that Leia was still around helping Ben to turn with the Han projection, even though she passed from the physical world earlier. That also solves the problem of having Leia’s body stick around until the end of the movie. I still think it would be interesting to show Han standing there before Ben drops the saber to really sell his surprise. There’s a lot of time of Ben just looking back there. Also, moving up the other Leia body scenes would give Kylo more time to breathe and ponder things before Han shows up.