Pick a park from
https://www.fs.usda.gov/
Navigate to the Recreation section and select that you want to do hiking then backpacking. You will be at a page that looks like this:
https://www.fs.usda.gov/activity/plumas/recreation/hiking/?recid=11182&actid=51
Pop open dev tools and run the following command from the console
[...document.querySelectorAll('#centercol li>a')].forEach(a =>
fetch(a.href)
.then(res => res.text())
.then(text => text.indexOf('This area is Open') > 0)
.then(isOpen => console.log(a.text, '-', isOpen))
)
