In the rules for Classic Cowboy and as I understand the proposed Hollywood Cowboy class, straw hats are not allowed, the reasoning is that they were not period and straw hats were not used in B western movies.
Watch "The Searchers." There are scenes with the Duke wearing a palm straw hat. The Mexican Vaquero that leads them to the Comanche camp is also wearing a straw sombrero.
Also get a copy of "Son of The Morning Star" and watch it. In it Maj. Marcus A Reno is wearing a straw hat at the Battle of The Little Bighorn. I have read historical accounts that state Reno was wearing a straw hat at the battle.
In the book "Archaelogical Perspectives On The Battle Of The Little Bighorn" Douglas D. Scott, U. of Ok. Press, 1989, ISBN: 0-8061-2179-3, on page 91 the author quotes researcher Jame hutchins in 1976 that some officers wore straw hats.
In the book "Custer's 7th Cavalry From ft. Riley To The Little Bighorn," E. Lisle Reedstrom, Sterling Publishing, ISBN: 0-8069-8762-6, on page 114, there us a photo of the straw hat worn by Gen. Ulysses S. Grant. The author states the soldiers were allowed to wear straw hats in the field that they purchased from post sutlers for 25 to 50 cents each.
In the book "Apache Wars An Illustrated Battle History" by the same author & publisher, ISBN: 0-8069-7255-6 are many pictures of cavalry officers, Apache scouts and even Geronimo wearing straw hats.
It seems logical to me that cowboys also wore straw hats in the summer. They were much cooler & less expensive than fur felt hats. A cowboy could more readily afford 25 to 50 cents for a straw hat than he could $4 or $5 for a felt hat. While photographs of cowboys wearing straw hats are very rare keep in mind that photographs were expensive and were staged mostly in a studio and a cowboy (or anybody else) wanted to look his best. Most cowboys bought completely new duds from head to foot when they ended the cattle drives in Dodge, Hays, Wichita, or Abilene and then had a photo taken in their finery for the folks back home.
Btw, when watching a DVD of "The Searchers" the other night it looked like John Wayne was wearing house shoes. It's in the scene where he is throwing wood on the fire next to Jeffrey Hunter, then goes to make his bedroll look as if he's sleeping there. We backed it up frame by frame & sure enough he's wearing light colored rubber soled bedroom slippers.
Now I'm not proposing that we be allowed to wear bedroom slippers and neither should anyone else.
But whoever drew up the rules for Classic Cowboy & Hollywood Cowboy didn't do enough research & they probably haven't spent a lot of summer days outside in 110+ degree heat.
One other thing Gene Autry, Roy Rogers, & The Lone Ranger had several identical hats provided to them by the studio wardrobe dept. that they would change when they got dirty or sweat stained.
I think it's time for a rule change. How about you?