I think that, as Justo noted, the scheme proved impractical because it "required a prohibitive number of machines" (and crews) to achieve the desired result.Well, not quite true. <snip>
Even if underwing fuel tanks let the Hurricane return to base after a reasonable time spent on patrol and in combat, the composite required (and risked) five engines, a much in demand bomber, a bomber crew, a fighter pilot, and a fighter to do a fighter's job. Even the CAM ships were probably a more practical/economical solution until merchant carrier conversions became available.
Since the Fw200, a rather fragile conversion of an airline, was the problem, I've often wondered why the fighter was even needed. Why not arm the Liberator with four or six 20-mm Hispanos and use it as a long-endurance, heavy fighter? I suspect that, once again, the Liberators were in short supply and needed for more urgent duties--like hunting U-Boats.