I'm sure the aerodynamics of the deep stall have been covered ad nauseam elsewhere so I will not repeat it all here.
Canards were considered, but the obvious disadvantage is that your main lifting surface can be compromised by living in the foreplane's wake.
As you can see in this diagram, de Havilland considered a rear-engined canard when scheming a trans-Atlantic mail plane in 1945, but access to the work of (inter alia) Lippisch changed all that.
