You'll be travelling to the Greek islands to see the polar bears, llamas, and elephants? And you'll be getting there by ferry down the Rhein? And you need a tripod to do star trails while under way? Yes, yes, I see, I see...
Have you thought of carbon fibre tripod to save weight? You'll be able to take more lenses then. And polar bear locators. And a EPIRB.
Cullmann have made a pair of good, big, light carbon fibre tripods - the Concept One 625C and Concept One 628C. they differ only in the length of legs - the 628C longer than the 625C.
Both have carbon fibre legs and centre column and twist locks. Both include an additional short centre column and associated tools for use when the tripod is very close to the ground. Both take a wide range of tripod heads utilising the standard 3/8" screw fitting.
Both have 10-year warranties. There are accessory bags available for them from Cullmann too - well worth adding to the list.
Note that the 625C will support 6 Kg and the 628C will do 7 Kg.
Hint: Don't trigger the EPIRB in the bar of the Rhein cruiser. They have no sense of humour on the Rhein.