When you cut out the hood did you rivet the crossmembers to the hood?
I don't know about all installs, but I think that would be a very good idea.
Or at least make sure it's bonded to the hood in one way or another anyway. Whether just "gluing" it with tape or silicone, or using the attaching rivets/screws from the scoop itself all the way through, something to keep the ends from bouncing around would be good.
And welcome to classicbroncos too while we're at it!
Why do we need so many rivets or bolts to hold it on? Would four or six bolts hold down a metal scoop?
Long life.
It probably does not take as many as are typically used, but how few you can get away with might depend on the individual scoop. And how floppy the hood panel is.
Over time, with the wind pulling at it and vibrations working at it, and heating and cooling working against it, a few extra for support would not be considered too much overkill I would not think.
Especially as floppy/flexy-flier as Bronco hoods might be after you cut the support in half!
Sure, a steel or thick fiberglass scoop can pretty much support itself on a few fasteners, but to me it seems like extras would be beneficial.
And at least a little part of it is due to looks. I think (and others may too) that the "fully riveted" look seems more, purposeful, stronger and custom fabbed, than just a few screws over that much real-estate would.
Just my opinion though. Some could very likely get by with fewer. But I would not necessarily want to be the one to try.
Paul