Notes from author
Not so much a recommended build, but wanted to show my character set-up for my SL1 character in NG+11.
By the time you hit NG+7 (MAX), almost every enemy will 1-hit you, so I did without any armor (no use really). Also, most enemies can bypass your guard since they guard break harder, so since guarding wasn't needed, I use the Grass Crest just to get the Stamina effect. I know a lot of people hate the Herpderp masks, but when you're solo-ing, anything helps, so I went with the Mask of the Child for Stamina regen as well.
Weapon can be anything, though the only ones you can use are Reinforced Club, Mace, Morning Star, and stuff. Nothing super hot here, so I recommend anything which can do as much DMG per shot.
The rest is simple, before going into a boss battle, with your HP at full, cast Power Within and let the spell wear out. By the time it ends, you should have about 100 HP which will activate the Red Tearstone Ring. Since you'll die anyway with one shot, might as well activate the Red Tearstone for MAX DMG. Also remember to swap your ring often as you need them (though I recommend using the Red Tearstone boost).
Aside from character set, beware that most if not all enemy attacks can't be blocked, so make sure you either evade or parry. Most of the bosses aren't that hard once you know how to tackle them (i.e. Firesage Demon, Quelaag, Iron Knight, Bed of Chaos, Nito, Gaping Dragon etc). Your real enemies are going to be Gwyn, S&O, and the Capra Demon . There is a way to tackle each one, so prepare to die a lot, but once you find out how with your meager Stamina and DMG, you'll hit a new level of awesomeness with the game!
BTW, the DLC bosses can be beaten with SL1. Your major obstacle is going to be Artorias, so a friendly hint in case you want to do a SL1 run (whether in NG or NG+7): your Light Crossbow and patience is your friend.
Good luck to any brave to pass the SL1 NG+ MAX challenge! Praise the sun!