The impression that I get from those buckles is that they're intended to be laced near the top of the shoe, not near the toe as is appropriate for formal ghillie brogues.

Using the method that you've shown, I'm a bit concerned that the buckles will be too high on the foot; though I'll reserve judgment until I see something nearer the final product.

As Sandy said, stitching them on or putting snaps on really ought to be quite simple for any cobbler and so shouldn't be too expensive.