There is no way in the world I would go up there and were a mask paddling across a lake, fishing, or hanging out at my campsite. I understand the principle but I will make an exception for my kids and I once as there is zero risk of others becoming infected.
The news stories calling it a mask mandate on all federal buildings and lands are overly simplistic and are giving an inaccurate impression.
Note that the order requires compliance with CDC guidelines. That will likely be something along the lines of having a mask at hand and wearing it when within 6' of someone outside your family/group. It is unlikely to include wearing masks all the time you are in the outdoors on federal land such as the situations you mention.
I'm not sure this is the "official" CDC guidelines but all I found: "CDC recommends that people wear masks in public settings, like on public and mass transportation, at events and gatherings, and anywhere they will be around other people." Suggests being in backcountry or wilderness alone or with your "bubble" group is exempt.
Help keep the flying moose flying by supporting BWCA.com