We used this material to keep the sun at bay in our Scamp TT & we have made covers using it in the Lance we now have. Works very well. In the Lance, which has sunshade blinds, we placed a sheet of it (sandwiched between to pieces of marine vinyl) between the blinds & the glass in the large window in the slide & in the side bedroom windows. We also added snaps to help hold them in place. Works well.
Reflectix Reflective Insulation can be bought at Lowe's or Home Depot. Works to keep out the heat.