Here is another bike that I have an idea about converting to SS.

http://www.trekbikes.com/us/en_US/bikes/mountain-bikes/cross-country-mountain-bikes/820/820/p/1008600-2017/

A review says that someone already made theirs a single speed.

I like how this one has smaller 26" wheels and is steel and costs less, however it is the same gearing as the hardrock.

also I'm told that surly makes the best conversion kit known as the singleator.