It was not actually supposed to be a hint

I am not giving you any hint until you are all really desperate (to which you may be close to, but not enough yet :d ), because seriously, there indeed are not many options - obviously a route via Dagorlad to Erebor and through the land of Forodwaith coming to Arnor from Angmar would be no doubt interesting for an army trying to surprise an enemy, but not as favourable for common use, trade etc.