We do this all the time, copy the boundary and paste it into the guidance layer, then I offset half the width of the planter. Yes this is a curve guidance, I usually rename it to "Headland". I then I make my straight "infill" lines and name them something like "North-South Planting" or something like that. I am not sure why you need a headland pattern for Field-IQ, it works just fine with a curve line and some straight lines. Are you planting the infill before the headland or something like that? As far as I know if you want a Headland pattern you have to actually record it in the monitor.