I choose to not go above 45#s over my head... or on my back for that matter - I'll add the 10# Cathe vest or 20# other vest for exercises I feel I want to but as a general rule I have to lift based on shoulder injuries that have never healed and tend to flare up.
Pretty much the same here.
My "over the shoulder" limit is 40-45#, depending on how I feel (thought that was pre-CLX, I think it might be higher, now!).
It all depends on what you can clean and press over your head and onto your back safely, with no 'fidgeting' or struggling.
I used to add up to 20# extra with an Ironwear vest (I now have an "undervest" for it, so I could go up to 40# extra), but if I really wanted to go heavy, I'd go to my Soloflex Rockit, where I've pressed up to 210# (no way I would try that with a squat rack without a spotter---or two!)
I picked up the Valor-BD squat stands a few months ago, because I don't want to put that risk on my shoulders, and while the Rockit allows me to go heavy, it's not quite the same as doing a squat (more like a hybrid squat/leg press, with more of a leg-press to it) and I want to do both.
While doing CLX, I've found that I can hold two, 30# dumbbells to do squats and lunges (though I've had some grip problems, even using straps or hooks, as the weights can slide a bit in my hands, and become uncomfortable).
Other options include adding a weighted belt (two ankle weights attached together). Ironwear--my preference for weighted accessories---has a nice set that takes the same wonderful (yes, I like them!) heavy rubber weights as the vests, and that goes up to 10#. I even know some people who use two belts at a time (you can buy the belts with weights or just the belt shell, if you already have the weights).
HTH!