For sure tints are the first move - for privacy & to keep things cool, it certainly makes things a lot more comfortable for whoever sits in the back. Aesthics are also a prime consideration - unless you are competent in tinting, pay a professional to do it - nothing looks & spoils a van more.... (except perhaps seam rot..)..than badly tinted windows. There are lots of new tints on the market - dark enough on the outside to allow you to get changed at the seafront without people knowing. Don't try it at night with the light on though!
For the front, at night, I like the outside screeens that Bluebird market, check them out...a bit less of a kerfuffle than the ones that stick on the inside with suckers - maybe not the thermal properties though.
In the rear, after tinting, most curtains will suffice to keep it reasonably dim in the van...if you still have a probem, get a panel van
