A No worries. Most of the leading lines do stock bed extenders for those guests who are 6’5″ and taller. Your travel advisor should put your request in writing and maintain a file cataloging your needs and communications with the line. But yours is not a unique issue and we see no reason to be concerned. The one fact you will need to have is the amount of daylight between the end of the bed and the nearest wall. We would suggest that you consider one of the window-facing bed accommodations on Avalon as they will provide extra space. Do be aware that there will be some low ceilings as you move about the ship.