Cheers Dave will check this as wellYou might want to look for rust holes under the arch, the metal gets porous and will let water in as it is thrown up by the wheel action, ask me how I know.
And the lens leak @Higgy mentions is also common, get someone to shine a strong light around the lens whilst in a darkened garage, if light comes through you have at least one source of a leak.
regards
Dave
Just to confirm .. thats the stripe below the rear sliding windows? Iv the same issue exact same spot leaking into bottle jack holderOpen the back door ad slide the plastic at the bottom of the window (outside) forward and off to reveal loads of holes Toyota put there with a little gasket on each to keep water out .