I rode the last 1/3rd of the "Around the Bay" last year with a hipster fixie dude - he did it on a dare and never wants to do it again.

The only spots that would give you any grief are the Westgate Bridge, and the climb up to Mornington. Both of them are surmountable though.

Be prepared for a loooooong day in the saddle and look after them knee-bones.