This route description begins from the suggested campsite in Rustler Gulch. In calculating the total mileage for Belleview Mtn., you should include the backpack(or hike in) from the trailhead.
From the suggested campsite, work back across the creek to the north and cross the main trail. Head uphill through the lush, flowering vegetation in a NNW direction, aiming for a small group of trees that appear to sit on a small bench. From those trees, you'll have a clear view into a basin that continues to head NNW, that's mostly grass & tundra filled with a section of some non-abusive willows higher up. It won't take long hiking in the vegetation with no trail to find your boots quite soaked from the previous evenings rain, if there's been any. And, once again, the flowers are so prolific, we were constantly stopping to take multiple photos. Utilize the drainage bottom to avoid tramping through so may wildflowers. It's also a little easier to see where you're putting your feet.
The going, once again, is steep, but not difficult. As you reach the upper part of the basin, there is another minor bench-like area with some willows. Work your way through. We flushed out some deer from the willows that quickly bounded away to the opposite side of the basin. We watched them some and took a few camera shots before continuing on. Tundra will carry you almost all the way to the saddle and even after that, as you walk west along the ridge, it is still on mostly tundra and some of the maroon rock found in this part of the Elks. Quickly pass over the no-count summit and head down to the pass, usually infested with hiking tourists, especially on weekends. It can be rather amusing to stop and watch some of these tourists struggling their way up or down the trail over the pass.
Now, begin the main ascent toward Belleview. This is the entertaining part of the day. At first, there's a well-used path that leads upward either by, around or through various rock obstacles. Much of the route is cairned. There was one section that led us on the south side of some cliffbands along a fairly wide ledge and after that, a brief and steep ascent up a rubble filled couloir and back to the ridgeline. We encountered more obstacles than we expected from our initial view of the SE ridge, but the going was never too difficult, though there was some route finding involved. It took us longer than expected to reach the false, southern summit of Belleview, which from a distance does not look nearly as high as the true summit, but in reality comes fairly close. By that point, you will be walking on almost exclusively, broken, flat platelets of maroon rock that the entire upper peak is made of.
From the false summit, walk north along the wide ridge. As you approach the summit block/pinnacle, swing to the right and contour upward onto the eastern flank and then turn up toward the summit for the final gain. As you approach the final section to the summit, the climbing becomes third class on highly fractured rock. This made holds for hands and stable positions for feet rather tenuous. Exercise quite a bit of care for the final 50 feet or so, and you should be able to stand on this enjoyable summit in short order. It had taken us considerably longer to get here from the pass than we had expected. On the summit, Maroon Peak looms over this summit and seems to dwarf it. It's an impressive view.
To descend, take a very careful descent off the summit block as you came and walk along the connecting ridge back to the false summit. Enjoy the view of the vast, tundra-filled Fravert Basin to the west. Retrace your ascent route as closely as you can. Then, it's back to the pass, probably still overrun with touroids, then head on up east to the no-count summit. From this summit, enjoy a dramatic view of Rustler Gulch and pause for more photos. Then, there's the long, continuous drop back to your campsite, and/or Rustler Gulch far below.
Links to other information, routes & trip reports for this peak that may be helpful.