Reflective bubble insulation at lowes or home depot. Buy a role, cut to fit each window. We measure the window, cut the insert 1/2" or so bigger and usually a bowl or can laying around the shop will have a similar radius to mark the corners for cutting. Pillows in the roof vents. Insulate, black out, paint or just cover the bath skylight if you have one. We remove the inner panel, paint, fill with reflective foil and insulation, reinstall, and coat with outside of the skylight with our preference of stuff.
All this done, you'll sleep till noon if you want, plus you'll help any RV out in the summer with maintaining lower interior temps.
John and Rebecca Dickson
Emma-13 / Little John-10 / Iva-7
2013 Ford F-350 Lariat FX4, CC LB PSD, DRW
2015 Jayco Jay Flight 28BHBE (#8)