I've found fishing at the castle there is never two days the same. You can fish in the exact same spot cast out more or less the same distance. First day you loose next to nothing, second day you loose everything including your temper. Try using lead heads with the hook on top it cuts down on tackle losses. Best Pollack of 8lb came on a lead head with an orange twin tail from the higher cliff top mark. If spinning would advise on using braid or a tougher mono line. If fishing the higher cliff top marks would advise taking a good quality drop net, nothing worse than seeing that fish of dreams coming up on the line then dropping back into the water. Believe me its not a nice feeling I know its happened twice to myself.
As for the hike to the castle from Craster its a lovely stroll that I always enjoy.
Please take a couple of black refuse bags with you for your litter and maybe take a little time to pick up some left by other anglers.You could leave the bags at the castle office/shop