You can actually farm sunlight medals from Falconers. The drop rate is quite low, but if you're not getting summoned very often it's probably faster. Falconers are the guys in the red outfits with a curved sword and golden falcon shield. The best place to farm them is at the Shaded Ruins, on the path to the Shrine of Winter. There's 5 there, right next to a bonfire. Brightstone Cove is another good place, there's more in that area but you'll have to aggro them one by one if you don't want to get overwhelmed. Make sure you wear the Covetous Gold Serpent Ring +2 if possible, Prisoner's Outfit, and Jester's Hat/Mimic head, as well as using rusted coins to maximise your item discovery. Also if you join the Covenant of Champions it'll prevent the Falconers from despawning, allowing you to farm them infinitely.