I know this is more of an exterior/appearance question... but it's mainly for folks that have installed stereo equipment, so I thought I'd post it here instead.
After getting my sub/enclosure installed last weekend, I've kept the cargo cover pulled back to prevent people from seeing the new sub. In my previous car, you could not see the sub at all, due to tinting and height (it was much higher up). However, in the wagon, it is very obvious when standing behind the car that there is a sub in the trunk!
I won't always have the rear cover in, and sometimes it gets in the way... is it enough to tint the rear windshield (and rear side windows)?