Volt Bike also offers a fender set. Same and the ones on their Yukon I believe. Again, looks like a fair price.
http://www.voltbike.ca/accessories/fat-bike-fenders.html
I bought a set of these fenders and still haven't installed them. I'm in Canada and thought that dealing with Voltbike would be easier. It wasn't. It took a long time to ship them and there was a lack of communication that was annoying. The rear fender should fit ok with some modifications but the front will not fit the 2016 RR without rubbing. There is no tire clearance without bending the fenders at an odd angle and maybe cutting them. The front might fit the 2015 RR better due to the different forks but would still take some modifications. I knew it would be a bit of a pain to get these to fit but tried them anyway. When the wetter weather comes back this fall I'll try fitting them up again.