I should mention that we also utilize those simple pop-open sun shades, made specifically for the E-series windshield. They keep the heat out so much better and also provide decent privacy given how well they fit the windshield. As of late, we've been utilizing the PC curtains for just the sides.
We had bought E-series pop-open sunshades at Walmart in their RV section of the automotive department. Ours are about 6 years old now, in need of new ones, now having trouble finding the same exact ones with that great fit.