Yeah, I had the same problem when I bought my EQ6 & wanted to mount my C11. In my case I was lucky enough to have a Losmandy style saddle to mount to the standard Vixen saddle (stolen from my CGE mount).
You can buy something like this as an example:
http://www.skiesunlimited.net/index.php?ProductID=5028
I'm pretty sure you can purchase the wide Losmandy style "top bit" as in your second lot of pics somewhere, I'm just not sure where..