The Vorderer Gosausee has everything you're NOT looking for as a visitor to this website: mass tourism, traffic jams, you name it.
The irony is that I have some understanding: the Vorderer Gosausee is truly the most beautiful lake in Austria - and that statement is based on more than 10 years of experience in Austria.
There are two ways to do this place justice.
The first is to beat the tourism. Literally: get up a few hours earlier and arrive around 8 AM (at the latest). The surrounding parking lots are surprisingly empty, there's literally no one around, and the sunset peeking over the surrounding mountains reflects beautifully on the lake. Highly recommended!
If you're not much of a morning person, there's a second way to explore this place: rent a boat. Granted, you'll have to get over your hesitation about spending money on what feels like a "tourist trap." But what you get in return is spectacular.
You can take an old-school (but quite beautiful) motorboat out onto the lake yourself. More than 10 boats simultaneously aren't allowed on the main lake, so you'll never be near others. You'll just cruise aimlessly, stopping at random spots to meditate while enjoying the beautiful view.
For the daring: bring a swimsuit and jump into the middle of the lake. My advice: don't touch the water, just jump in (spoiler alert: it's colder than you think).
I took the boat tour with my family (2 adults + 2 children under 10), and it was surprisingly well-received by everyone. With a budget of less than 50 euros, you can enjoy an hour or two of adventure (for us, it was a rush to get back on time).