Frank, this for FUN, you don't do fun???
I enjoy making things, as well as climbing mountains and taking photographs and probably a hundred other things you may consider absurd. I shall continue with my little project despite your apparent disapproval.
Thank you for the pointer to a very delightful designed panoramic head. After delightful design, flimsy was the first thought which came into my head (pun intended!).
Can you imagine my D3 and Nikkor 300mm f2.8 mounted on one of those heads... I shudder to contemplate it and the flimsy head would probably shudder too/ The nodal point of the 300 f2.8 is about 215mm BEHIND the lens mount. Not quite sure how your suggestion would handle that. My design will handle it with aplomb and will be rock solid. But perhaps you consider using the 300 2.8 for panoramas is absurd too?
It may be absurd to you but I will enjoy making it and using it that's is more important for me than going out and spending a lot of money on someone else's excellent and artistic design. You never know, others may like my design and reproduce it themselves.