Well, better late than never. There could be some chance for good old Edgar landing with a crusade force in Spain in 1070s. After all, in 1063 there hasd been a calling for a crusade to liberate Spain from the Moors. He might had given a hand in 1067 to free Saragossa from the Muslims and could have found himself involved in the civil war between Sancho, king of Castille, and his brother Alfonso, king of Leon.
Perhaps the victorious Sancho isn't murdered and may give some fiefdom to Edgar, if the Aetheling manages to perform some heroic or useful action. If he's still alive when the Almoravids under defeat Castile-Leon at Sagrajas (1086) he may going to see interesting times...