Super I am currently shopping for the same thing and here is what I have found so far. I am also 5x5 1/2x20 thread.
I knocked one of my wheel studs out just over the weekend and it measures .524 on the knurl. The smallest stud I can find has a .530 knurl and the length is the same as this one. I too am going to a longer stud. So, I'm gunna buy some studs that have a .560-.565 knurl and just trim the axle a bit if that knurl is too large to pop the cherry