Hi Kate,
interesting question, the ecoinvent datasets are more for larger planes, thus won't fit perfectly, although they allocate per person or ton km thus scaling down the overall impact of the plane. Larger planes may be more efficient but also heavier and faster and thus consume more. So ideally, you model your own plane dataset for this, but can use ecoinvent's datases as a proxy.
Then, I would assume your case is a mix of freight and person transport, so you can select either; and I would model per distance (so, person or ton-km) and convert the area to the distance.
Hope this helps, Andreas