The tail was removed and I got on the bike, crouched down, and moved my arse back and forth along the frame top behind the tank. The height of my line of sight did not change. The top of the helmet eyeport was the controlling factor. Years ago I tried that trick of crouching way down and looking at the signs as they passed by for orientation. My balance went off and I almost crashed. Talented folks can use that method, not me. I need to look forward. My helmet does not meet FIM approval so there is an opportunity to address the eyeport height issue.
The new FIM approved helmet list has few options in Size XL. They are specialized race helmets and none are available off of the shelf in the U.S. I need to guess at the proper size and order the helmet from the UK. The local shops cannot get them 'cause the distributors do not stock helmets that do not have DOT or Snell approval. There are options in XL from manufacturers AGV, Arai, LS2, and Shark. LS2 is Chinese and us Oregon folks have no experience with Shark. We do know that AGV and Arai make good lids. Arai is preferred by most racers here.
Helmet comparison tests say the AGV has a very good unobstructed view when crouched down. They also say Arai is OK in this respect, too. The Arai helmet is sold in the US as the Corsair. It does not have FIM approval. The plan is to go up to the shop in Portland that has lots of road race helmets and to try on the american versions of the AGV and Arai helmets, find the size that fits, and order the approved helmet from the UK in the correct size.