PF's suggestion of OB sounds like the only really good option. Huge, wide beach, often few people. Sinlce you sound determined, I would add: Practice with a kite one or even two sizes smaller than you would need to actually go out riding. Preferably not a brand-new one, either.
Of course, learning someplace safer doesn't mean you'll be safe when doing it someplace where the launch is small and surrounded by obstacles.
As PF's post suggests, the biggest problem with self-launching is that it's only safe if it's perfect every time, and most methods of doing it involve some degree of uncertainty.