That route (Point Clear to Mersea) has also been suggested to me by PM and sounds good (assuming I can get my trike on the ferry). We used to have our boat at Brightlingsea and I remember a rather small boat which was a foot ferry... might struggle with my trike on that... but that might have been the water taxi.
Anyway, the route is only very hazy so far in my mind and I would love more suggestions/improvements - we have two months to refine it to an excellent route. If I have (as looks likely) a mix of CycleChatters and YACFers we could be 25ish people so would have to bear that in mind for any unusual modes of transport, like boats.
My German cycle holiday route doesn't exist at the moment, apart from me going by train from Hook of Holland to Köln and then setting off south. It will no doubt change considerably over time as with my average daily mileage I could probably do the entire route three times, so I may branch out on the Main river as well. Although I'd have to buy another book for that
I intend to do a thread with my progress on CycleChat and I'll probably stick it on here too somewhere, if people would like.