As I said, I've been working on mine with a 320 wet.
The 600 was "kind-of" working but when compared with a portion that was covered by stripes/letters, it was pretty obvious that the colors weren't the same.
I could hit-it with the buffer and it would shine-up nice, but you could tell the color was still faded.
When you say "haze" what exactly do you mean? Haziness could be caused by not getting all the scratches out from the 600 grit. I doubt this is your problem though as you are using very small incriments 600-800-1000.
The haziness is probably due to not getting all the way through the oxidation. (This was my problem.)
When I started with a fresh sheet of 320 and worked wet, I noticed that it worked much faster than the 600 (obviously).
I then took-out the 320 scratches with 600 wet, took-out the 600 scratches with the buffer (cutting compound), finally got-it to shine with polishing compound.
I knew I had it right when the water imediately beaded-up and the color matched the stuff that was under the vinyl.
Try to replace sand-paper frequently as it does wear-down (sometimes leaving a few "sharp" spots that leave scratches).
A squeegee helps a ton when wet-sanding so you can clear the water-off. (Water makes it hard to see the scratches.)
You can def use some 320 or 400 or something dry, on an electric to speed things-up like wiatowski did.