Perhaps you can compromise and go with the segno on the right side and then nudge the rehearsal mark and segno sign over a touch so the double barline is between them. It will be apparent that the barline is where they apply. I think this is the case of simple preference.
I did double check the “bible” (Gould) and she says, “The segno and coda signs go above the stave (or top stave of a system), centered over the barline.” (pg. 240)
For good measure (no pun intended) I double checked the rehearsal marks guidelines (pg. 485) and she recommends centering the rehearsal mark on the barline or flush left with it. (ie- the left edge of the box lines up with the double barline). So if anything, you should move the rehearsal mark, not the segno sign, and place the rehearsal mark to the right of the segno sign.