All of the five 13er summits that we have placed in the Buckskin Pass Group can be accessed as a day-hike from the Maroon Lake TH. It is possible to also backpack up Minnehaha Creek and set up a base camp from which all five summits could easily be done in about two days. UN13,039 we have sequenced with Buckskin BM for a fairly long day-hike from Maroon Lake.
From the Maroon Lake parking area, head south on the Crater Lake trail #1975. Make sure you don't get diverted over onto the scenic Maroon Lake trail. Walk 1.5 miles to Crater Lake amid hordes of dayhikers, touroids, etc., unless you've gotten a good early start. View the "Deadly Bells" warning sign. If you're going to backpack in and camp overnight, you'll also need to self-register. At Crater Lake, turn west and head up Trail #1978 toward Buckskin Pass. This trail heads up Minnehaha Gulch and begins to gain some serious altitude shortly after Crater Lake. There are/were some backpacking campsites near the lake and the trail intersection. At about 11,100 ft., there are/were some excellent campsites on the ridge to the right above the trail if camping overnight. They are located a short distance before the trail crosses Minnehaha Creek at 11,060 ft. It's about 3 miles to this location. Be sure and check recent regulations regarding backcountry camping in this area in case a designated site system has been implemented.
From where the trail crosses over Minnehahah Creek, continue a little farther toward Buckskin Pass. At a switchback on the trail at about 12,080 ft., you can break off the trail and head toward UN13,039 and its north ridge. (You can of course also continue to the summit of Buckskin Pass as well.)
Follow a mostly tundra-covered slope more directly toward the summit of UN 13,039. This route will take you through something of an enclosed ramp and then on to the north ridge of the peak, just below the first cliff band. This first band requires one little rock climbing maneuver over an 8 ft. slab that we surmounted by jamming a foot in a crack. Near the summit, there is one other minor rock and cliff problem that required a little more scrambling, and then, you'll arrive at the summit.
Links to other information, routes & trip reports for this peak that may be helpful.