Donald did indeed have the Fairbourne screens on his 3 Wheeler. So do I. They are very good, reducing buffeting considerably. Fitting them is quite a fiddly job but well worth it. As for the legaility question, I do not know the answer. I can still look over them to see the road ahead but perhaps some owners might be prosecuted for being too short.
Another vote here for the Fairbourne screen. Not too tricky to fit but they do a fitting service if spanners are not your thing. Reasonable price. Much better wind and rain protection and as they are a bit wider than the standard screen your outboard hand is not in the full blast of the airflow.
Lovely colour planetnut . I was driving in the rain yesterday with my small screens and wondering about how the visibility would be with the Fairbourne .
Not ideal visibility in the rain as you may have to sit up a bit to see over the top, or use your hand as a wiper. Nothing is good in the rain, you have to wipe a full face helmet or goggles. The bonus with the Fairbourne screen in the rain is that it does give more protection, the water doesn't run up the bonnet and land in your lap as with the standard or Brooklands screens. On the move you stay fairly dry, no help when you stop though. The colour is Jaguar Bordeaux Red by the way.