On dragy my truck has gone 13.7 a few times... I can't seem to 60' better than around a 2.0 and if i could get that to a 1.8-1.9 id have a 13.4-13.5 slip.
solid write up. i think your trailer weight guess is a good amount off though.
your trailer empty should be 5600-5710lbs or so.... GVWR is the max your trailer should weigh while towing WITH gear/water/etc counted in.