As far as lei set up is concerned I don't see any difference apart from different size kites for different winds.
But perhaps a different type of kite is required. Light weight one the will drift and launch well. Particularly in the ultralight winds.
I have changed my harness set up to slider rope, low friction ring and cut down my chicken loop to make my set up 10cm shorter. That has certainly helped with foiling. Mainly on the hard upwind tack and any toeside action.