Just how things are.

Find somewhere to go backpacking for a few days or go on hikes.

We're doing the John Muir trail. From mammoth to Yosemite it is a five day hike and you can get walk up permits starting 14 days out online. Stay in mammoth at a rental for the other week.

You could also do Cambria south of big sur in a rental and do a bunch of day hikes.

But I don't think you'll get a communal food type thing with activities by age.