In the winter our unit is completely covered (Michigan--doesn't get used in the winter). In the summer while in storage I cover the front windows with a similar foil inside cover. I picked up 3 from Camping World and cut them to fit:
Multi-Purpose Foil 4' x 10'
While we're camping I cover the outside of the windows with a
Sunguard RV windshield cover. This guy has the advantage that during the day you can look out and people can't look in--like a heavily tinted window. At night we have to close the curtains because the effect is reversed (more light inside than out).
This way I don't leave my sunguard on the RV during storage (don't want it to weather prematurely since it cost a lot more than the 3 foil panels), it won't get stolen, and/or won't get blown off the camper.