A little tape can add an extra layer at your thin spot and be helpful for any emergency repairs.
I use a clear packing tape (see below) on the fore and aft centerline. It is surprisingly durable and if applied dry, there is no problem with it coming loose when wet. It protects the hull nicely; when it shows signs of wear, it's easy to replace. The premium tapes appear to be more tear resistant than the thinner cheap ones, so take a close look at what you choose.
Others have used Duct tape for emergency repairs. Like the packing tape though, it needs to be applied to a dry hull.
I believe there is an aluminum skinned tape also available -- have no experience with it though.