Congratulations on the new trailer and welcome to the forum.
Hopefully someone with a similar unit will have something to offer. My first thoughts are the obvious ones; windows and ceiling vents closed and the thermostat(s) set on 'cool' and to a low temp. Other than those, I got nothin'.
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.