I'm at this same point with my 32 roadster build. I did not like the (IMO) "unfinished look" of the open corner area between the gastank and the frame on my fenderless Rod Bod highboy.

Steve's Auto offers some metal corners that can be fab'd to fill the area but there a little pricy at $350/pair. So, I took a damaged cruiser motorcycle fender and cut it down the middle and then cut some patch panels out of the halves for the "compound curve" part needed for the corners. These were installed on the corners with some flat sheet stock on each side formed to match the original body lines. It looks much better now.

Sorry no photos yet.