I have a very live and let live attitude but in my experience the few kids I knew they got into heavier substances did so because the parents participated in the "Normal" substances with them. Whatever the parents where into was the baseline and so in order for those friends to achieve that cutting edge vibe they needed to go to the next step, whatever that was in their head because no matter what mom and dad did that was boring. I'm not saying it's always going to go this way but a majority of the kids I know that ended up doing really messed up stuff where either drinking with or using a bong with their parents (Robert Downey Jr. Style) from a pretty young age. As a result when I had kids I went as straight and narrow as possible so that my kids really didn't have to try very hard to be renegades rotfl. for my part, I'm strict and easily shocked by them so they get that rush not having to work too hard for it- so far so good
So using this logic, my very successful, super responsible Dean's List son is going to become a heroin addict because my DH and I drank a beer or two with him on our family vacation???!!! I think you are making a huge leap here.
Believe me, I totally get the fear and anxiety you are feeling about your first born going away to college. DS just finished his first semester of college. It is VERY hard for me to get used to the idea that he has a whole other life that I am not a part of. He goes places, knows people, has experiences that I know nothing about. But that's the way it should be. Our children grow up.
We had an alcohol policy in our house while he was in high school. He was allowed to drink in our presence. He was not allowed to lie about where he was or what he was doing. He was not allowed to drink and drive. He knew if we caught him he would lose all privileges - car, phone, allowance, etc. We did not want him to feel the need to "sneak". We saw lots of other kids put themselves in dangerous situations due to "sneaking". If he was going to a party and wanted to have a few beers, he had to tell us. Then we either made arrangements to pick him up, or he spent the night there. This worked very well. He came home hung over one time and one time only. That's all it took.
He soon realized that he is not a big drinker. He likes to have a couple of beers or a couple mixed drinks, but he doesn't like losing control, getting sick, or making a fool of himself. I am very grateful he was able to figure this out about himself before he went away to college. He just joined a fraternity. During rush he eliminated all fraternities that had bad reputations for drugs, disrespecting women or were too heavily focused on alcohol consumption. He wanted a "mild mannered frat" - his words - and he found one. He is very happy! And I am very proud of the discernment he used in making his choice. He does drink at college…he showed me the fake ID he ordered online so he can get into the bars. All I said to him is that if he gets caught or gets in trouble, the legal expenses are his responsibility. Of course I DON'T WANT ANYTHING BAD TO HAPPEN TO HIM, but he has to be accountable for his own choices now.
His college has a huge alcohol awareness program. The kids are taught how to identify if someone is in danger, when to put a backpack on them when they go to bed (so they don't sleep on their back and accidentally choke on their vomit), when to call 911, when a female student may be in danger of assault. The students take looking out for one another very seriously.
As for the whole GPS thing…I don't even know what to say. I do not track my DS, nor do I check to make sure he goes to his classes or is home by a certain time. He is in college for goodness sake! My parents didn't know what I did, where I went, if I skipped classes or not when I was in college. They heard from me once a week on Sunday afternoons. Again…it's called growing up!
OP, you sound like you've done a very good job raising your son. When he goes to college, you need to take a step back and trust that the life lessons and moral values you taught him stick. Have faith in your son, and have faith in the job you did parenting him.
ETA: I also have a DD, a junior in high school. We have the same alcohol policy for her. She has had a few drinks with us at family parties, but she doesn't really drink with her friends. She went to a blow out party her soph year - cops called, kids wheeled out on stretchers, some taken to intensive care. It was a sleep over that went terribly wrong. Mom left the house, info went out on social media. That party blew up HUGE! Luckily we knew where she was, and she texted us to tell us what was happening. We were able to get her out of the situation safely. She told us later that she texted us because she knew that we'd told our son that as long as he told us the truth about what was going on, he wouldn't get in trouble. She hasn't been really interested in drinking parties since that.
However, I strongly believe she needs to know how alcohol effects her before she goes away to college. I really didn't want her first drinking experience to be in college. There is way too much risk of sexual assault.