I ride the Oregon portion of your contemplated route quite a lot . I would suggest you consider doing the route N to S if for no other reason than the ocean is off to your immediate right. From S to N the ocean is across the road. I have used a Bob trailer with a mountain bike/touring bike (26' wheels) on this route and although I do not load the trailer heavily I appreciate having Avid BB7 disc brakes. With thoughtful gearing and an exercise program (do your squats!) you'll have a wonderful time.