I realize this is a long thread but I thought I'd post an update.  After NNielsen educated me on my coordinates being slightly off I did some reading on the Ardusimple website and realized I could also get the exact coordinates of my antenna by using another NTRIP RTK service if I had one available.  Fortunately, I used one for one of my tractors so I configured my setup as a rover and used that service to get an RTK fix.  I recorded the coordinates and then entered them as fixed location.  My initial testing appears that if I am not exactly perfect I'm within 1/2".