Jesper,

One of the lower priced 12" or so portable surface planers work fine on full length strips. Good uniform thickness seems to make the planing, scraping and sanding stages easier. Maybe you have a buddy with a planer? I live in the San Diego area if that is any help. I have not used Cedar on a kayak yet as there seems to be none around here that is fit for the fireplace and nothing even remotely suitable for kayaks. I hope to pick some up on my next trip to Oregon and Washington. I use good clear pine for the main kayak and either redwood or Phillipine mahogany for trim. The redwood is not really a friendly wood, it seems brittle and cracks easily. Check Nick's book for wood information and ideas.
Good luck and have fun. Hope to see you on the water. Dave