Hi ZeroID,
Well I was considering the carbon over aluminum, but also the Easton X7 Eclipse target arrows. I use those to shoot indoor target and the are twice the diameter of a standard arrow which make them stiff. If I do go with an arrow shaft design then a 2 piece design with a center ring will probably be the best option for two reasons. First, the increased rigidity and second having shorter shafts improving transportation.
With that said there are also companies that make larger carbon tubes. I am also looking into these .5" OD tubes. They are 48" long and $14.70US ea.
http://www.dragonplate.com/ecart/categories.asp?cID=102