Your challenge is to have the Knights Templar conquer the Canarias and setting up their base of operation there.
Meh, the real Templars would be much better, I only give you half a point.How 'bout this:
1418, Henry the Navigator as Grandmaster of the Order of Christ leads an expedition to the Canaries. They succeed in subduing the island and establish a base for future exploration/conquest.
It's not the Templars, but it is one of their main successor orders.