Actually, I think the RCM stats will make the mod easier in a lot of ways. Metal armour is a lot more effective now, and arrows do cutting instead of piercing damage so you won't be pincushioned. I found long spears/pikes the most difficult part of the game (since M&B's engine can distinguish the shaft from the blade of the spear), but now they're less effective on armour slower as per realism.
So, unless some factor is being forgotten by me, I think the game will actually be easier once you get some good armour. It'll only be a .txt download and you'll be able to keep your saves, so you could try it out once it's finished.
EDIT: I have the file up: https://www.mbrepository.com/file.php?cid=8&id=1328
This is only the first version, so quite a few items will be wrongly statted, or even left entirely till I get some advise. Play around with it if you like, the majority of it should be fine.