+1 on the freehub-having non-disc rear wheel and spacer combo. If you want something a little beefier than PVC, Spot [and others] have aluminum spacer/alignment kits that allow you to easily fine-tune chainline. If you need a tensioner, I would just use an old derailleur [road ders work great]. Surly [?] makes extra-wide splined cogs that fit on modern freehubs and will help prevent the splines from being rounded off the freehub.