I have been thinking about this for over a week. this is what I have come up with.

the roof of my cab is - i think fiberglass as its not magnetic. It requires 8 holes to be drilled. They part includes self tapping screws, however to me this wont work very well.

I was thinking of use some stainless steel bolts, washers nuts and lock washers. preferrably fender washers on the inside. I was also thinking of how I could tie all the bolts on the top in line with eachother so that they are 'interconnected' and thus becomes a stronger bond to the cab. The way i was thinking of doing this, is using some 1/8 in flat stock aluminum, or maybe stainless depending what I have in stock, I dont want to use steel as I dont want to worry about rust issues in 10yrs. I realise i could blast, prime and paint the steel ,but would prefer to use a non rustable metal.

Cut the flat stock so that it alligns with most of the holes, if not all. I realise I will need more than one piece.

I was thinking in this way, from top to bottom,. the visor on top, between the visor and the cab have a layer of silicone then the bolt thru the roof, will be loaded with silicone, then glue the flatstock using construction adhesive to the top of the inner cab.... then the bolts go thru predrilled holes, and the flatstock will sandwich the roof of the cab to the flat stock and the visor.

By doing it this way, it makes sense to me that the stresses of the visor will be spread out much more effectively over a MUCH LARGER area and thus it will resist movement and vibration alot better. I know that I could just tack it on like everyone else, however it seems to me theres a 50/50 result base out there where it works, and it doesnt work. I feel my way will work, and not only that, but last forever. and it will NEVER come off - which ofcourse could be a major downside.

What do you think? I think the installation for most is probably in the area of 2-4 hrs. for me im looking at days as I will have to fab up special brackets...