Man the box is the most important part of your substage... I'd go with a pro... I went with Mobile Enclosures and can't recommend him highly enough, though I'm sure there are others out there that are great to deal with too.
To me, it was worth the few extra bucks to get exactly what I wanted out of my box design.
---------- Post added at 04:08 PM ---------- Previous post was at 04:08 PM ----------
Clipping them with 1/2 power, on the other hand, will be incredibly hard on them. Set your gains right, be careful, etc.
And before an argument starts, no, you can't really underpower a speaker. But you can underpower a speaker, it's much more complicated than that, but set your gains so you aren't sending the speaker a square wave and you are all good.
If underpowering a speaker alone blew it, you'd blow speakers every time you turned the volume down.