I consider MTM a bonus for the LL so I would not up charge and can’t offer any other advise.
Whatever your local avg rental charges for rent of like-kind. Rentometer or other rental sites will give good idea of where to be.
You should rent for market rent regardless. Type of agreement is irrelevant. I would only charge extra if you knew going into the agreement that it was going to be short term. Whose idea was the M2M, yours or tenants? You should be calling the shots and using whichever agreement you’re comfortable with.
I do m2m cause it’s easier. I wouldn’t charge anything different. This isn’t a method that costs more or less IMO. Just continue with your agreement and enjoy your tenant.