Go for it but only if all parties are in agreement. Getting married young is a dream killer so if the girl wants to get an education or do something worthwhile I would advice her not to honestly.
But by playing devils advocate, I can see why you want a young Xalimo; because once they get exposed to the real world they lose all their innocence and become saqajaans. That's why many Xalimos and Faraxs lose their virginity in college and become waste yuuts. It's more than you think too.