How wide do you want the head to be.
If it's too wide I would think it would actually be quite hard work to use.
You can get landscaping rakes which are 3 foot wide, but they are only really designed for light work like like levelling bark and shingle etc..
If you want something more heavy duty look at tarmac rakes, they use them when hand laying asphalt, I have one thats years old but even that is only about 18 inches wide, which is about the same as a decent soil rake.
Apart fromthat have you got a decent Blacksmith nearby, you could go and tell him what you want and he could make you a custom one.