I've been lurking on this thread, but had to add support for LJ here:
As a fellow recipient of stalking, I know how frustrating it is not to be able to do anything about a stalker. LJ's right, unless they physically harm you - you pretty much have no way to file a restraining order, sometimes even with written proof. I live in CA, which is one of the most progressive states in the Union, and I still couldn't get a retraining order even with batches of letters sent to me, pictures taken by friends, and verbal testimony from witnesses.
I had to move 100 miles away to be rid of him and not be constantly looking over my shoulder...
Unfortunately I have no advice to add, LJ, other than giving you my support and hoping you decide to pursue legal action. It may be a hard road, but I hope you're successful.