We used to fly standard Rogallos off Crestline. Generally we landed somewhere along Devil’s Canyon Road. So modern equipment should make it out to AJX no problem.
The briefing I give to H2s is:
If you get lower than the ridge, consider going to the Billboard. If you’re lower than the houses by the house thermal, definitely go to the Billboard.
Never try to cross directly to Marshall. Marshall is well rounded, so while you won’t hit a well-defined rotor, you will have sink in the area behind it out to about the middle of the canyon or a little further. Think of it like a very large, very oddly shaped airfoil: the air wants to stick to the surface, so it goes up on the front side, and down on the back.
So if you don’t clear Marshall, and try to sneak around, you will be in sink the entire way. There’s a little bit of a venturi wind effect at the end if you’re below the top, too.
Instead, stay as tight along the back ridge as you reasonably/comfortably can. Even if you don’t climb back there, the air, in general, is going to be going up, and extending your glide.
Go down to the Billboard. There’s a ridge there that points toward the powerplant. If you’re at or below 4800 feet, head out to Marshall.
Fly along that ridge parallel to the big tubes. Generally a little to the left of the big tubes is where I’ve found the best lift. Bearing in mind that there can be some venturi effect in the mouth of the canyon, when you can clear Last Chance or Regionals, do so.
The bailout isn’t very good, but it’s the closest thing to landable terrain in the canyon. Figure on a crosswind uphill landing. There’s a steep dropoff next to the road. It’s fairly flat, though pretty bushy, next to the edge, but it gets steeper and steeper the higher you go.
More advice, I can’t give, because I’ve never landed there, only picked people up. But I think I’d try to set up diagonally, to try to get some headwind component and a shallower path up the hill.
I think it’s better to leave Crestline a little early and have some altitude to work with when you arrive at Marshall. Yes, it’s possible to get up from very low in the canyon, but I don’t think the risk is worth the reward.