I can't count on both hands the number of pilots I've known who said "Oh, I'll never fly in bad weather/fly down in a canyon/etc." And, many of them wound up doing just that, with grim results.
I teach canyon turns with 45 to 50 degrees bank angle, max LIFT flaps deployed and a hard fast pull with full power. This is a level turn, NOT a climbing turn. As often as not, people in canyons (real canyons that is) tend to gravitate up to the very bottom of the cloud layer as they go up canyon. And, as they mosey up canyon, the bottom of the canyon gets higher. By the time turning around becomes necessary, climbing isn't an option, and if you like, DA can create the very same scenario.
I've done this in Beavers (the VERY notorious BAD turning airplane that someone actually created a NEW WING for, because of it's terrible characteristics in a turn

), Cessnas, Cubs, Huskys, Scouts and several other types. It is a maneuver that MUST be practiced in advance, since a VERY few airplanes don't respond well to this maneuver, in which case, you need to know what bank angle/how much pull to use with THAT airplane.
I enter the maneuver right close to Vy, in other words, slowed down, but not slow. Flaps to max lift, generally half flaps. Initiate a roll, and as you roll through 30 degrees bank angle, push up full power and pull to turn. I have had precisely ONE type airplane stall on me in this 180 degree maneuver. Done properly, it's over in a very few seconds. Yes, the stall horn blares if one's installed.
I first learned this maneuver when I was flying in Kodiak, where there are a LOT of canyons, and some weather occasionally. I was being checked out in the Beaver by a VERY experienced deHavilland pilot. I asked him about the reputation the Beaver has for being a killer in canyons and bad weather. I then demonstrated this maneuver a hundred or so times till I was doing them in my sleep. And, that notoriously dangerous airplane in canyons turned like a Pitts.
Yet, lots of Beaver pilots have died in these airplanes trying to turn around in a canyon. The wreckage is found near the bottom of the canyon, turned about 100 to 120 degrees around the turn, spun in. Why? Because they didn't slow down and CONFIGURE the airplane for the turn.
Anyone who thinks their airplane will stall, come fly with me and let me show you what the airplane can do, and do safely.
This is NOT an everyday maneuver, but it needs to be practiced.
Believe whatever you want to believe, but a year or so after I checked out in that Beaver, I found myself lowering the flaps, slowing it down, and turning in a tight canyon that I almost made it through. I was right at the cloud base, so climbing at all was out of the question. I could ALMOST see through that canyon, right up till I almost got there, then.....turn.
Piece of cake, with good instruction and practice. I perform this with every airplane I fly. The only airplane I've ever found that wouldn't REALLY come around in these was a 7GCBC...it stalled halfway around. So, lighten up the bank a bit and figure out what THAT airplane wants.
Every airplane and every scenario is potentially a little different. Idaho is different from Kodiak, which is different from the Brooks Range, which is different from Colorado. Are you there because you don't have the power to go over, or because the weather is holding you down? Density Altitude makes a difference, no doubt. At high DA, your indicated airspeed will have you flying at a higher true airspeed. That means the radius of your turn will be greater.
Finally, to make this work, you have to learn to use linear control inputs. Roll with coordinated rudder and aileron, neutralize those for a heartbeat, then pull to turn. It's the pull that gets the airplane turning, and it MUST be linear, which takes some practice. Aerobatic training and discipline really helps here.
FWIW,
MTV