TV-76 and ToUcam

Tried to get some photos of the eclipse last night using my TV-76 and a ToUcam 740K. With the diagonal in place, couldn't reach focus. Took out the diagonal and replaced it with the 2" TV extension - I was able to reach focus, but could not get the full lunar disk. Does anyone know if the 0.8x field flattener/reducer would shorten the focal length enough to get the full lunar disk?

John in NEOhio

Searching another forum, someone posted that a 300mm focal length is the longest that will allow a full disk lunar view with a webcam. So, it doesn't sound like the 0.8x reducer will get me where I want to be as it only results in a 380mm f/l on the TV-76. Can anyone confirm that 300mm statement?