what are you strapping to? you might try wrapping the stave in an old belt , to give it some grip. i use old belts for everything from pads for clamps , to an impromptu strap wrench. your imagination is the only limit.
you might want to try using some of that standing deadwood to make a shaving horse. im sure one or two of those stumps , and a chainsaw would pretty much put you in business. i know you have a hatchet , so that might take a while , but like you said , ya got 9months at least. might want to do a little prep work to make things easier on yourself down the road (ie : once your stave is coming to look more like a bow , youre going to want a solid lock on your stave.).
if thats out of the question , you might try affixing it to something like a 2x4 with rope at the ends. its extremely crude , but thats how im straightening some wood i cut a while back. this option would allow you to still use your straps too...
i know you got duct tape over there...
-hov