In my opinion Herc should work by far the best with provisional forest, due to the great synnergy with her relic weapon with it. That means, the soul won't be covering any debuffs, besides the def down from the burst effect. Best use for her therefore is f.e. fire, where B frames are covered, A frames generally aren't and they have no other way to get Shingen's pf to work 100% safely.

Now for light, you don't necessarily need sniper either, you could just run tsuku and artemis to get max def down with herc, prob sol and then either Eros/Rapha for more atk down, or you just go full damage with Frey or Michael. Either way, for light imo a Shingen build might be the better choice, but gonna have to try each of them in action.

Another thing that seems kinda popular on dmm are Light control builds (like Tsuku, Artemis, Sol, Eros) with Morgan to add single target heal and provide the necessary damage with her 2 turn 100% group rampage.

@Aidoru: Why would you sub out Artemis for a Shingen build? The big advantage of running shingen over other pf builds is that you can run sniper and comfortably hit 50/40 with Michael, Tsuku, Artemis and Sol (or sub out Sol if you need more damage over heal). Without Artemis, you'd still be missing debuffs, unlike with a Herc+Sniper build (which i'm not really all that convinced of yet).