Why aim for a barley beer OG with sweet potato ?
I mean if you were making a Shiraz you'd probably aim at 1.08 to 1.12 for an OG
Maybe sweet potato beer needs a lower OG and will keep fermenting to a very low FG.
I know potato based vodka starts at a quite low OG of course I haven't tried to make it as it's not legal to do so in Aus
I might try a 5l brew next time we have an overabundance of sweet potatoes - using that linked method for extraction.
I'll just go for a decent amount of mash and not worry about the OG.
As for your cock beer - I get food poisoning walking past KFC so no chicken in my fermenters .
Cheers
edit and ps.. Just boil those boys and non layers and make some heartwarming soup instead.