if you're really worried about it, you could put a layer of fiber glass on them to limit flexing. this may make them thicker than you want, so they could be sanded a bit before the fiberglass goes on to make the end product the thickness you want.
my 8.5' blades only has ~8" of tower clearance. granted the blanks were laminated from multiple pieces of clear fir. then i put one layer of 6 or 8oz (can't remember) fiberglass on them. they are VERY stiff.
it looks like you welding is complete, but it is also possible to tilt the entire (blade/rotor/stator) assembly back by a few degrees. you could just drop in an angle grinder w/cut off wheel into the main connection point, bend it back a bit, then re-weld it.
either of these ideas sound far better than carving a new set of blades!
adam