Busy busy Jacek, ha ha, love it, fill free to invoice me for the RPP 300m support btw.
I definitely am in on this mount for the canon 1DIV if not for anything to be used as Location scouting and Director's view finder, when my Epic-X is fully loaded and set up on the sticks.
Love the design and especially useful to me is the handle, which I wish you did something similar for the 300mm as well, just like on the support you sold me for the 18-85.
As far as been able to have 15mm or 19mm rods you should definitely make it part of the design it self, a must have.
As far as the bottom plate, I love the concept but it foes not need to be one piece, in fact I would love it much more if it was two pieces, so that one, you don't need to by the bottom piece if you don't needed it, and second, it will not be on the way when using the camera hands free as a on location still shots and or as Director's view finder.
Lastly I'm only interested really if it does clear all RPP and RPZ including the 18mm and the 300mm, the 17-50 and 18-85.
If all the above described is a possibility then you know my name and address he he, just invoice me.