What style are the pull-down shades?
If they are pleated or honeycomb style, then can easily be replaced with blackout versions. You can probably find them at Home Depot. There are also ones that have both translucent and blackout sections. Definitely a worthwhile improvement.
Formerly: 2005 Airstream Interstate (Sprinter 2500 T1N)
Now!: 2014 Great West Vans Legend SE (Sprinter 3500 NCV3 I4)