I am thinking about driving the family to Vermont to ski at Killington for a few days next week.  Reading the Vermont's requirements, it appears that the required quarantine period is to be done at the home state.  Has anyone been to Vermont recently that could shed some light on how the resort is enforcing this requirement?  Do they just take the testament from the visitors on an honor system?  

We have been isolating ourselves from the public as much as we can since my mother, who is on the high risk category, is living with us; but we are not quarantined per se.  Just to be on the safe side of compliance, we are planning to get tested at a community testing center scheduled for later this week, but I am not sure if we will get the results back in time for the trip.

Yes, it's possible to self-quarantine before driving to VT and have that count.  I know people who live in CT who are willing to do that.  Also possible to quarantine after arriving in VT.  VT residents who go out-of-state (discouraged at the moment) are expected to quarantine after returning home.

Not sure what the "attestation" deal is in general for ski resorts, but for Ikon passholders they have to attest online that they are going to follow VT travel restrictions before their Ikon pass is activated for VT resorts.

Have heard only a few stories of lodging owners turning away a potential customer who clearly hadn't quarantined before going to VT and wasn't planning on staying in their room for 7/14 days before going to do something in VT.  The general sense of people who are VT residents is that at least some of the people with out-of-state plates aren't following the travel restrictions.  It's generally understood that there is no organized enforcement.  Like everything else related to COVID-19 legal mandates and public health guidelines, dealing with travel restrictions is complicated.

https://apps.health.vermont.gov/COVID/faq/#travel

I just returned from a week long trip to Stowe with my college aged son. We did quarantine for the 14 days prior as this is his only trip this year before returning to school.

Vermont is pretty serious about precautions. Every exit off the interstates has fixed/permanent signs warning visitors about quarantining. I did not eat in any restaurants but while picking up take out I could observe people who were eating in had to provide contact tracing information. As we were on Epic passes there was no attestation done but that may be part of the Epic reservation system. My email confirmation from the hotel had some vague language about attestation but that was it.

The parking lots (Stowe, restaurants) were full of plates from all over the east coast, we saw from Maine to Florida. I found everyone working at restaurants, stores to be extremely friendly but they are serious about mask compliance and following whatever rules/setup each establishment has. Read the sign before entering any restaurant/store and you'll be fine. PM me if you have specific questions, I'd be glad to help, I was super nervous but the trip went well.

Thank you Everyone for your advice and guidance.