In my mind, double coating is a waste of time and materials.
I single coat with plenty of sensitizer, and my negatives have a tonal scale appropriate for kallitype. These provide me with excellent d-Max as well as a good tonal scale.
I do gold tone on occasion because i like the color.
I don't like the idea of coating the finished print with polyurethane, but have waxed occasionally. I prefer not to do either.
It sounds like your clearing may be inadequate. You should be using a minimum of 2 clearing baths, changing them as soon as the second shows any color. Three clearing baths are much preferred, again changing as soon as #3 shows any sign of color.
My normal procedure is to make the first rinse with acidified water, a little citric acid, and clear in three baths of EDTA + sodium sulfite. This process clears most papers for me better than any other combination.