I don't see Warren getting as many touches (if any) this year. I feel like we might see 2 running backs in the backfield at times. I really can't wait to see Kene.
I'd say
70% Montgomery
25% Kene/Croney
5% Lang/Warren
Montgomery will not get 70% of carries. If we average 40 rush attempts per game then that would be 28 carries per game. No way. Look for him to maybe be at 50% of carries. Or 20 carries per game.
Mike Warren will get a few carries. Maybe average a couple carries a game. Lang about the same. Croney and Kene will probably get about about 6 carries apiece her game. And there will be some QB carries as well. Joel Lanning had the second most carries last year.
Campbell will keep Montgomery fresh. With the running backs we have it is foolish to pound him as hard as you are suggesting.