Yes, you can set the region of the s3 endpoint easily: Here is your build tweaked to set a s3 region and endpoint:
deploy:
provider: s3
edge: true
bucket: "skinnybrit51.com"
endpoint: "s3-website-us-west-2.amazonaws.com"
region: "us-west-2"
upload-dir: "booty-grid"
skip_cleanup: true
secret_access_key:
secure: zDiuEZgn1THVJyvqE4FcKXPXY/Aozy2gm1gHDkHCooVoZuRtU31tz1N6zWp3yVJ3JZFk4zDO7zyWGjtAba5ydh8FNOl+F/L0RVpYfiSpoiJA7PZlXAw1WKPiyY21luCctZeJc/eZry8ZseM190Q+UzbiqLLjtteO1CHeZo3XptM=
access_key_id:
secure: yj/T/lSSr1MMyUZMiS2IGqvFG78ExJQi06wxa5+7M2Rfz1G5LaiVH+9mqcE5qVmu1q54/CmwT1OUNdeXy/SUOwre4L7ZshS9LfK/7BcATMjIvCSysNT3AEOIx63NtRWabzQMiQu25h5owVbvwTBMN6N6+C/g5yq46XQsvoy6xz8=
local-dir: public
on:
branch: master