Can you use a wide range 11-42 cassette with a double crankset Can you use a 10 or 11 speed wide range (11-42, 10-42, or 11-40) cassette with a double crankset? 

I know these wide range cassettes are typically built for a 1x setup on a mountain bike, but is there any reason why you couldn't pair this with a front derailleur and run it with a double crankset? I would assume to be running a type 2 clutch rear derailleur anyway to support the wide range and reduce chain slap on smaller cogs.
An 11-42t cassette as per the title, no. An 11-40t however as you mention, yes! Shimano has the answer here. So if you're not already tied into SRAM then I'd jump ship to Shimano. They have the answer to your question.