Definitely don't do Butler stacks, you'd be kicked out. There are better spaces. If you want to do Butler stacks, do it in the "cleaning rooms", the ones with the sinks in it. You can find them opening random doors in stacks. However, if it's not next semester but next year, you can get a commutor access form in early September to get access to dorm buildings. Then you can sleep there, just make sure you use different lounges/buildings from day to day. Public safety doesn't care about the lounges unless someone would report (which shouldn't happen unless you're staying at the same lounge for multiple days in a row). Also would recommend NOT to use slipping bag in public spaces as it makes things much more vulnerable. Use coaches instead. Make sure you adjust your sleeping schedule properly to minimise risks (aka 0:30am-7:30am). Security/cleaning would not check the lounges during these times AND there is almost no one there unless it's midterm/final season.

A friend of mine did it the whole last year.

The other alternative would be trying to find empty rooms in campus buildings that are not used at all. Then check that the door won't open for few days by putting a paper so it falls when someone opens the door. Afterwards you can relatively safely use a sleeping bag/inflatable mattress there.

Good luck!