I'm going to say the same thing I just posted on your question on UXExchange:
The best solution is what you have in your question - a single touch performs the hover effect. This works just fine on an iPhone and is completely intuitive. I tap a nav item, and it expands to show the secondary nav items. I tap it again, it takes me somewhere (if it is itself a link). I don't see the need to replace something that already works and makes sense to the user.