Retired teacher here but my DH is still teaching middle school.
First, masks are mandatory for all staff and students regardless of age or vaccination. This is week three of the school year. DH's school has twice as many of COVID cases as they did all of last year. With the exception of 3 students who have a class together, none of the other students have any contact with one another during the school day so they're pretty sure it hasn't been spread at school.
So where did they all get COVID? There were a few sleepover parties after school started and every one of the students who have tested positive were at one of those sleepovers.
Second, we have very good friends who took a multigenerational family vacation to Alaska. All eligible family members have been vaccinated, there were two under 12 who were not vaccinated. They traveled and slept in two RV's and as well as cabins. Every family member returned home last week and tested positive for COVID.
I would absolutely not send my child to an overnight trip at this time. Yes I realize that the friends who hang out do so at each other's homes without wearing masks. However, putting them in a more confined space such as a bedroom, hotel room, or cabin type room were they are sleeping, talking, etc for 8 hours without masks is not a good idea in my mind.