At this point I believe that none of them allow it aside from the one day at cooper. How aggressive they are about enforcement varies though.
Many of us have ridden them, and quite a few of us have received "a stern talking to" if I recall someone got as ticket for riding eldora (CO 2.O & JP?)
but that's the only one I've ever heard of.
the ones I know for a fact that don't allow it:
breck,
keystone,
vail,
loveland (they used to allow us to ride there, it was great when the snow started getting punchy in late spring as it was compacted there)
winter park,
eldora
The others I assume don't allow it, but these are the ones I KNOW will go after you for riding there.
I parked right at peak 9 one day & rode all day long without an issue, had a great day, the next weekend I think powdercowboy went up there & was threatened with a ticket if I recall...
Lots of us thought that it was legal once they closed, but their lease doesn't "expire"... their insurance still has to cover them for liability, so if they "allow" us on the mountain, they're open to suits from riders who hit a pipe or something like that. A few years back someone totaled a sled right on a ski slope by hitting some kind of equipment... that kind if thing can't help.
One day I got to hit one of the parks that was still in place after closing... best day ever
![Big grin :D :D](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
They're all pretty aggressive about plowing the parks closing day now though.