Thanks! I’m sure we’ll find out more about Snoke in the future (maybe even in Episode IX) but I’ve been trying to think of ways to kind of hint at Snoke’s backstory. This is just one option, and this way you technically don’t have to change anything related to him in the ST. As soon as we see him we would know who he is, and although the movie wouldn’t tell us how he survived, Palpatine would have hinted at his abilities to “cheat death”, so we can assume he somehow managed.
Whenever we get more info on him, I’ll probably think of ways to hint at that backstory more in the films, but this is one option at least. Another I was thinking of would be to insert a very brief cameo in Return of the Jedi. For example, in the scene where Vader goes to tell Palpatine that Luke is on Endor, Palpatine has his chair turned away from the door. Maybe here, you could insert a hologram of a less-scarred Snoke in front of Palpatine, as if they were having a conversation that Vader interrupted, and the hologram quickly fades as the Emperor turns to face Vader.
This idea would be implying that Snoke may have been an advisor to the Emperor, and it wouldn’t necessarily be out of place because there is another scene in ROTJ where the Emperor is with his advisors. With this idea, Snoke was an advisor, maybe a dark side acolyte, who was already located in the Unknown Regions, and came to power once the Empire fled there. Maybe Snoke, after Sidious’ death, was trying to learn the ways of the dark side to resurrect the Sith. It would be an interesting inverse of Luke. This idea would be a lot easier to implement than the Snoke/Plagueis one, and you could make the hologram very brief so as it really wouldn’t hurt the sanctity of ROTJ, but still be enough to foreshadow his character for the ST.
Also, Kylo Ren’s line, “It’s time to let old things die. Snoke, Skywalker, the Jedi, the Sith, the rebels, let it all die.” This line seems to imply that the Sith weren’t totally dead, which leads credence to both ideas. With Snoke=Plagueis, even though Snoke may not have identified as a Sith anymore, he still had that knowledge and power. With Snoke as Advisor, it would also imply that Snoke was trying to keep the Sith traditions alive.
And like I said, the new canon might eventually come up with another backstory for him, but it would be cool to try to plant some hints to whatever it is in the films themselves. And if IX gives us backstory for him, then I’d just go with that. But until then, these might be two options to consider.
EDIT:
For Return of the Jedi, I’m referring to this scene.
https://www.youtube.com/watch?v=85EEB_-fkQw
This ILM VFX Reel has a cool 180 pan around Snoke that could possible be used to have his hologram at the right angle in front of Palpatine, although a part of his head is cut off, so it would either need to be added back on or covered up with a hood or something
https://youtu.be/69Ld3phO1V0?t=26