There is no smooth ride route on that track in summer with the heat we have been experiencing at any altitude below 12k or so. Keep in mind that the ground begins to climb from Redmond south, KRDM is at 3k, KBDN 13 miles south is at 3400 and S21 (Sunriver) is 4100 and change just 20 miles further on. If you hold altitude you are actually losing altitude AGL which can not help. Later in the day even 12 is rough. Coming from the valley you can be in fairly smooth air until you hit the crest of the Cascades. The pass between Mt. Jefferson and the Sisters/Mt. Washington complex just flat out hammers you as you cross over. The only thing you can do is fly early or late.