The usual front squat, done with an Olympic style grip, is impossible for me. Even with all the various drills. That's reality and I'm fine with that. I messed around with the Sting Ray but it didn't really fit well, though with some messing around it did work.
A few weeks ago I saw a trick in an article using some common wrist straps. The kind you use for deadlift or other pulling motion training. You wrap them on the bar then grab the middle over the bar and hang on with the bar balanced in the indentation of your deltoid muscles. See the video here for a better idea of what I'm saying.
One thing to keep in mind is that in spite of my lack of wrist flexibility and stability my lower body and legs are in fairly decent shape that way. I'm going way down here. If you attempt any kind of squat check out the curve of your lower back just above your hip bones - if you lose that curve at any point in your downward motion that's a little too far for your current flexibility or mobility. They're two different things.
Do what's right for you, and when in doubt have an honest intelligent friend help you out, or hire someone who is qualified.