You could in theory make that possible with the addition of the Gain Support at Various Ranges patch -> set to whole map.
Then you can do math to calculate how many turns it would take for each rank.
For my own hack, I made a support calculator in Google Sheets that does the math for you. All you have to do is input the starting value and value per turn and it tells you how many turns it takes to get from unranked -> C, C ->B, and B ->A.
If you're interested, I can share the sheet with you (It'd be nice to have somebody double check my work, lol).