Was this the 45 minute video on packing light? I have never seen it so took a quick look. Perhaps Rick got things started off wrong by demonstrating a backpack as his travel luggage. Where else would your daughter get the idea you would be camping? Actually you need MORE stuff for camping, not less, so perhaps you could straighten her out on that. The girls (and maybe your wife?) need reassurance that they will not feel deprived at all if they pack wisely.
We took our tween and teen daughters to Europe 4 times before they reached adulthood—-once to London and Paris, twice to Switzerland, and once to Italy, all 2 week trips. The Italy trip was a graduation present, for one graduating from college, the other graduating high school, so they weren’t teens any more, and by that time they knew the drill.
It was only the first trip that was difficult, when we told them we were going to pack into carry-on bags only, no checking luggage. And it was only the older girl, who was 15 at the time, who complained, mainly because the liquid restrictions meant she could not take her makeup, face scrub, and her favorite expensive shampoo. We promised her a shopping expedition for replacements in Paris, our first destination, but she never took us up on that. Maybe because we presented it as an opportunity to practice her French, which she was learning in high school. Anyway, she survived on the hotel toiletries and the few items of makeup she was able to fit in her 3-1-1 bag. She did manage to fit her flat iron (for her long hair) into her carry-on and fortunately it was dual voltage so she could safely use it.
She totally resisted the notion of practical, lightweight “travel clothes” instead of her fashion jeans, and we didn’t push that one. We settled on 4 pair, including the ones she wore on the plane, and we ended up doing laundry a couple of times (an adventure in itself in Paris). For shoes they brought sneakers and flip-flops, and one time a pair of Uggs, and we didn’t argue that one either. Then there was the bulky hoody sweatshirt with a bold Abercrombie & Fitch logo. I tried to talk her out of that, arguing that it would just shout “American tourist!”. But she insisted, so we said she could bring it but would have to wear it on the plane and whenever we were in transit since it wouldn’t fit in her suitcase.
Ironically, it turns out there was an A & F store in Paris., so she fir right in. And there was even a knock-off store we passed on one of our walks, with the name spelled Abercombie in letters very similar to the real one. ( but without the “r”). I tried to find the photo we took of that store but it is hopelessly buried in thousands of travel photos. But I did confirm that I wasn’t imagining things, as I found a Facebook page and a Yelp listing for them.
https://www.facebook.com/profile.php?id=149695708432289&paipv=0&eav=Afap71IJVaOGvX7e8iwdtIsWgT9mopLMev8SnO4q_dJ21gjEfaJH_-RpydQLhKxjgbQ&_rdr
https://www.yelp.com/biz/abercombie-paris?osq=abercombie
You have to pick your battles carefully with teenage girls; I am sure you know that all to well. Here, I would be firm about the luggage size (carry-on only), pointing to all the horror stories about lost luggage* from last summer and the recent holiday season. Point out that they can also have a “personal item”—-a large purse or tote bag—- but they will need to be careful in some places. (When we were in Milan, DD1 had a nicely-dressed older woman tap her on the shoulder in the subway and remind her to keep her large purse, which was dangling from her shoulder, zipped up).
As for what they put in that one piece of luggage, try to leave that up to them, unless they actually ask for advice, or propose to bring something so outlandish and impractical you just have to veto it. If they make mistakes, so be it, and they will learn a lot. Just don’t let them skip a rain jacket if you are going to Switzerland.
TBC . . .