I interpreted the same part about the mounts being inline, where you have the tcase/trans/crank in a line. I thought the tcase mount had to come off the same cross member as the trans mount.
I could be misunderstanding the thread as well, but I thought the potential issue with the two cross member mounts being parallel and each connecting to the frame is that if the frame rails were to get in a flex each cross member would move differently and cause the tcase and trans to move separately. As apposed to one cross member would allow the frame to pivot independently.
I'll be re-reading the thread several times when I go to build a support for my doubler setup
Maybe someone smarter than me will chime in
Edit: maybe I am misunderstanding. Hydromatic seemed to be well educated on the matter and this is how his mount is - similar to yours with two cross members
And this is what I was pictured, with the trans and tcase both sharing the same frame side mounting points.