Some of these ideas are alright, but I personally prefer the first one (taking place circa 40 ABY) than the second (circa 11 ABY), so you can delve into the future generation of the Jedi. Sure a lot of it seems complicated, but like with anything else, it’s how you approach it.
In case of Mara Jade, I’d hide her away for Episode 7, only mentioned-not seen-in dialogue between characters, e.g. Luke talking to young Ben (who could be Anakin Solo’s pupil), saying that his mother is proud of him. When episode 8 comes around, we’re introduced to Mara, secretly fighting off the Sith invasion and through that, you can delve into her backstory, allowing her to act as the Yoda of the ST.
Something similar would happen with other famous EU characters. People like Kyle Katarn and Corran Horn can be shown on the Jedi Council, Talon Karrde is head of the Smuggler’s Alliance, Pellaeon working with New Republic Intelligence, and so on. Each of these would be more or less side characters, who still manage to shine in their own way, as they use their political/Force prowess to learn more of this oncoming threat, and you can even have them become involved in the battles of each installment, with the Jedi using the Force to coordinate and destroy Sith soldiers, and non-Jedi helping to infiltrate the Sith. Same can also apply with EU worlds, like Ossus (which can be used more for Episode 8).
Also, and most importantly, I’d suggest to not make Ben or any of the Solo kids turn to the Dark Side. I found it dumb and stupid in LotF when they did it to Jacen (who seemed like a good character before the shenanigans of the 2000s books), and if you’re canonizing the EU/Legends (specifically the Bantam era of books) in your ST, you’re better off without that.
… And that’s all I can think of right now. I hope this helps.