I don't do singles, but I have been doing 3, 4, 5 rep sets recently and I think that I have a method to build up to the big weights that might help you. At least, it works for me.
I warm up with:
2 sets of 135 x 8 or 10
1 set of 225 x 8
a walkout with 475
If you don't know, a walkout is just when you unrack it, step back, and just bounce up and down six inches or so each 'rep'. I'll usually do ten of those. You're getting your back and, most of all, your mind ready for the heavy stuff.
I'd then start my work sets, right now at 405 x 5, and then work up to my last, heaviest set at 475 x 2. But if I wanted to find my single rep max, after my walkout I might do 405 and 455 for singles. And then jump into wherever I think that my range for that single rep max would be (right now I'd guess 525 a good place to look, but I've never actually done it so I don't know).
I agree that you need to cut back the weights, as you've already addressed. I suspect that if you scale my weights to what works for you, you might have success with it. Good luck!