Hi Raphael,
With Footwork currently, the footnotes will always be placed abutting the left, right, and bottom margins of the page.
So, since the margins must be used to define the maximum width of the footnotes, perhaps a workaround for the main text is to apply a large text-frame inset for the main text frames. This can be set in their object style.
Your screenshot doesn’t show whether you’re using mirror margins or whether the margins are the same recto and verso. If they’re the same, I think there’s a good chance this idea will work.
If the design does involve mirror margins, it’s more complicated, but a similar workaround should be doable.
Another idea is to include a blank rectangle with text wrap on the master page, to create the main-text indents (and this would work whether or not you’ve got mirror margins). Then you can set the footnote frames’ object style to “ignore text wrap.”
Would either of those ideas help?