I don't think it takes much to anchor the plastic tube adequately. I have two kayaks with cable tubes like that and i just used a few short (3") pieces of aluminum duct tape. I'm meaning the kind of tape that is actually metal, aluminum and has a peel off backing (not the plasticky gray stuff that disintegrates after a while). As for routing I just made it as direct and smooth a route as possible while still dodging the hatch.

Ric