Velvia can work great in full sun, you just have to be sure to expose using the Sunny-16 rule instead of your meter and make sure there is nothing deeply-shadowed in your scene. At Sunny-16 with a CPL, you will get deep dark skies, perfect foreground-exposure and nicely-exposed bright-but-not-blown clouds, it all comes together quite well.
OTOH, Fuji says it's fine to pull-process it by one stop by reducing the duration of first-developer. You could certainly reduce contrast that way though it might have an effect on saturation.
And introduces a color cast, they don't mention that.