I wanted to check if I would still need permission from fan scenarios (assume so)
You’re correct: you do need their permission if you want to include their scenario text in your submission. However, you can mention and link to fan scenarios without getting permission. Then you can spell out your changes to them in your campaign submission (just like you did in your example).
The one thing to keep in mind is is word count for “referenced” scenarios: the word count of scenarios that you link to in your campaign still count against your campaigns 30,000 word count.
For example: you’re planning on using Last Things Last in your campaign. LTL has a word count of 1,514 words. If you don’t hear back from Bret Kramer and instead need to just provide a link and remix notes (like you currently are doing), the link to LTL would take up 1,514 words of your 30,000 word budget (plus the 38 words you use for remix notes).
The reason for this is to keep a level playing field regardless of how an author performs a “campaign-stitch”: submissions that get permission and include/remix the full text of pre-existing scenarios are at no disadvantage compared to submissions that just link to pre-existing scenarios, and neither have exceptional (dis)advantages compared to authors writing all their own scenarios.
if this framework instead of a full written campaign is even fair game for the jam
I think that framing your submission around Labyrinth-style Stage progression is definitely allowed and in the spirit of the jam, But you’ll still want to fill each Stage with scenarios (either of your own design, or using your current “campaign-stitch” technique).
Hopefully that was helpful. Feel free to ask follow-ups!