Did you get the regular or the small?
I got the regular. It´s 5,25" (I´m 5´9). Small one is 4". I am told the length is kind of much for some people but I feel that this packer is completely realistic for me, there is no serious bulge going on unless you are planning on wearing something really tight.
Did you find an STP that worked better? In the end I made an STP that can be used separately from the packer. In my experience packer/STP is just too awkward and messy. So I decided to be able to STP comfortably rather than have a realistic looking STP.
If you´re going to experiment in making an STP I recommend just getting a bunch of crappy packers first and see how that works before you alter an expensive one.
Do you sleep wearing it as well? Yes. I´ve been using the "Pete" Commando harness by SpareParts Hardwear for all three years. You can´t even feel its there and it looks natural, like any other masculine underwear.
Does it need to be powdered? The back of the packer can get kind of sticky, but my packer sits atop 1 layer of underwear, so I don´t really notice that. I would recommend powdering as it will extend its longevity. I think if you bother to take good care of it (which I didn´t) it would last very long.
Good luck to you