I’ve been messing around in AE.
I feel like we’re likely to see Hayden or Ewan as a ghost in IX so I wanted that reflected in VI, but I dislike the creepy footage of Hayden that Lucas used for the Special Edition. My idea was that the two ghosts are elderly men in the first shot of the ghosts (just like the OOT) - they appear to Luke as he knew them. But then in the second shot, as they watch the rebels celebrate from afar, I felt it would be nice to see them as the young heroes of the Clone Wars they once were (especially if they do appear in TROS as I suspect). Based on Ewan and Alec’s voices being used in TFA, and Luke force projecting his younger self in TLJ, I don’t think it’s unreasonable to imagine force ghosts can appear however they wish to.