They only say that to cover their butt. All you really need is larger washers. But if you don't want to "make it fit", wait for the F6B model.
It fits just fine, just need thicker rubber washers as mentioned above. I actually emailed National about 8 months ago and asked them if they were going to make a specific shield for the F6 and they said they would work on it. I guess they are still working on it, but the Goldwing shield does install easily as is. I did get some scratches under the shield from it rubbing, but was told by a Gold Wing owner that the shield does that on regular Goldwings too.
Today I had an 18" Wind Wings windshield installed at their shop in Plant City Fl. and I really like it. It is their stock sized GL 1800 replacement shield. No problem and easy install. We used the GL1800 "slider?" type windshield insert washers and smaller nuts. The windshield is similar to the F4 shield. As I have both now-- one on the F6B and one on my GL 1800 I will be able to compare them for wear and Optical clarity. I also had them install their mirror wings. They are 2x stronger, thinker and better made than the baker wings I have on the GL 1800. The metal hangers etc are all stainless steel an visually thicker and stronger looking. Good product and they are attending Wing Ding, Reno and several of the south east GWRRA rallys this season.
I had a BaggerShield 11"/19" convertible... was fine. I looked over the top when it was in short mode. Tall mode made things pretty quiet for me and the GF, but I had to look thru it then.
I just installed a Madstad 11"... nice change for me. Much quieter in the cockpit now, even though I still look over the top of the shield. I haven't use it with the GF on the back, yet... but I suspicion it will be just fine.
So far, I like the Madstad better. I'm 5'8" and using the stock seat.
"1.21 gigawatts?! 1.21 GIGAWATTS??! Great Scott!!"