Given that meat is high in purines and the breakdown of purines ultimately results in a large amount of urate, the excretion of which is increased by Vitamin C, one might reasonably assume that we paleo folks would find benefit in supplementing ascorbic acid daily. This is only one of many ways that animals use the vitamin, but it's one whose need would scale up with meat consumption. The urate decrease from less fructose would probably be to some extent balanced out by an increase from purine nucleotide breakdown.
While the SAD may increase the need for Vitamin C for some other reason (due to the increased fiber intake maybe as well as massive fructose intake maybe?), I'm not certain that the dismissive attitude toward vitamin C that I see often in our community, such as it is, is warranted.
Dogs apparently endogenously produce roughly 18mg of C per pound of bodyweight. In times of stress, they produce quite a bit more. A 180 pound paleo werewolf abomination might then manufacture 3.24 grams of the stuff.
Given that we humans are incapable of any endogenous production, one may desire to supplement with this surprisingly non-toxic water-soluble vitamin in similar doses.
I would however recommend against consuming fructose-rich foods in order to obtain ascorbic acid, especially if one is attempting to lose fat, since fructose is one of the most lipogenic substances known. To say nothing of the fact that fructose increases urate levels itself.