Welcome to the JOF.
Sorry I don't have an answer to your specific question. Hopefully someone in the group will have a similar trailer and an answer for you.
Coupler height varies due to trailer frame differences, how the coupler is attached to the frame ('on top' or 'underneath') and the suspension of the trailer (some trailer frames are higher off the ground than others due to slides etc.).
Sherm & Terry w/rescues Steve (std Poodle) & Eydie (min Schnauzer)
2015 Jay Flight 27RLS (Camped: 102 nights 2015, 90 nights 2016)
2006 Ford F350 6.0 PSD, Lariat, 4WD, CC, LB, SRW, auto., Camper pkg.