I don't have any experience with this paper, but I do use the front fine art feeder on the P800 all the time. I haven't had a skew in a long long time.
The Canson website gives the thickness 466um for the heavier version of this paper, so, as I understand the printer driver, the paper thickness in Advanced Media Control should be set to "5" (for .5mm, which is 500um). This could be what's causing the skews.
I don't know whether the platen gap should be set to wide for this paper. I use "standard" for Canson Baryta Photographique (and "4" for paper thickness; it is 310um).