Specialized Cirrus 4 groupset upgrade

So I have a lovely Cirrus 4 that I call my adventure bike. Currently I am running the stock groupset that I would like to upgrade. This bike currently has a hyperglide hub and threaded bottom bracket. What I want to do is get a nice 1-by front ring and have a bigger range in the back. I am totally happy sacrificing speed for hauling so I would like to get something like a 42 in the front, and a 11-42 in the back. I don't have much experience with these lower tier groupsets and where the mountain bike compatibility starts and ends.

Has anyone done any kind of rebuild like this?