What you are failing to see is if having soil that can grow patches of veg makes a viable business. If you can grow veg here and there, and have irrigation etc, then get it let for veg/pots.
Lots of people can grow spuds but how many do in their own right? Few and getting fewer. Why? not becuase they dont want to, but capital costs and lack of end user contracts. Big spud growers have all the best contracts for the super markets etc.
Clay of any type will not be able to match the light land boys for veg and roots. As we are talking viability, lets consider the capital inputs for field scale veg growing......they are not small. Do you want the hassle of specialist kit and all that dicking about? Where are you going to store it/sell it etc?
Another way to think about it being viable, is "can I find or create a niche product with a local demand?" Could you grow roses on it? What about herbs? How about lavender etc that you could get a grant to process to a finnished product?
Field scale veg production in your own right? Sorry but it is as simple as "no". Better if you want to do that would be to rent some land more suitable, as the base land rent is only a tiny factor in this sort of crop production - fenland silt growers are growing more than one crop a season on their land.