Having moved a bit with work we have made friendships based on the above and mostly in that order in both motorsport and camping/4wding circles. Whilst our closest and longest lasting friends from this are similar in age we have had great times with some younger and many older who are still pretty young at heart. You learn stuff along the way with the oldies too just don't admit it to them or it goes to their heads!
So much truth here.
We're in our late 30's with 2 kids under 8.
I also moved interstate for work, we found some great friends when we joined a local 4wd club.
But to go against the grain of this conversation, our closest friends from the club have no kids and are almost literally twice our age.
We can drive all sorts of tracks with them during the day and have a blast, then sit around the fire and chat all night.
It's not the age, it's the person.
And by the way, we're on the Sunny Coast now and our family is usually camping somewhere at least once a month (often more then that). Put a shout out if you're planing a trip somewhere, we might tag along if we can.