If you're still coming to Namibia around May to August you can at least be sure not to catch much rain. It's still one of the features of this country I consider to be the best: reliability in regard to the weather :-)
Make sure to bring your GPS along - there's still plenty of unmapped roads and places.

Well, yes: QuadMapping is really the fun part of it. You reach most places (even through narrow tracks roads) and you can easily carry whatever you need for a picnic or a sun-downer.