The only method that makes complete sense is an adjustable bellows-style compendium shade. Glare can come from other angles than just above, like in reflected glare of snow, ice, or water below. And one needs the ability to adjust the compendium just right, viewing through the clipped corners of the ground glass at the taking aperture. The Sinar system has a rod and clips available to turn a spare of their basic box bellows into a compendium. On my 8x10 folder I use the Lee compendium if necessary, but I also have a very light option for both my 4x5 and 8x10 folders, which shades just from above. I'd avoid ordinary hoods like those used on small cameras without view camera movements. A Stetson hat works only if you're equipped with a bent nose and beard too.