I just finished a red oak lam bow but it didn't use fibreglass lams. I agree with Shredd that the open grain in some of the rings might be an issue, depending on how it is oriented. I would try it with good quartersawn wood but probably not with flat sawn.
FWIW, the power lam and tip underlays on my last oak bow were 0.100" thick tapered down to nothing on the ends and I had no issues with the grain. I think down to 0.075"-0.080" thick would be no problem with careful selection of the wood for grain pattern.
Mark