Growing sweet potatoes was a valiant first attempt on my part, but in the end: All Hat, No Cattle. The harvest I dug in mid-October was a combination of very large, pest-damaged potatoes, and fingerlings too small to eat.
The fingerlings were the size of long skinny carrots but they will get tossed in the root cellar with hopes they will last until spring to grow some new slips to plant. (That's now iffy; we had an unexpected hard frost last night, and they were still laying out on the ground.)
Close-up, there was a lot of pest damage which appears to be from voles. Also, a bunch of the potatoes looked like they grew fast, stopped, and then grew again, splitting the skin.
The vines were very thick, affording lots of cover which kept my cats from hunting in the bed. There was so much vine growth that the hilled rows were not even evident, just one huge mound of vines. I didn't see any vole tunnels when I dug, but I was using a fork which would have spilled soil and obscured the tunnels anyway.
You can barely see the SP bed in the right half of this photo, taken mid-September. The bed was 10 feet wide, with 3 hilled rows about 12-14 feet long, but in retrospect the rows were too close together.
I learned a lot by growing sweet potatoes but I'm very disappointed that I have none to eat. Sigh.