I spent some time up around the Brunswick Heads -> New Brighton end back in the 1980's; haven't been up there in more than a decade now...
However, I do remember that stretch was quite suitable for roaming nude back then, especially during the week - wouldn't know about these days, though..
Ah, "...those were the days, my friend; I thought they'd never end."
No,Belongil is the one beach I dont visit. I generally go to Whites beach, Brays hole or Kings beach. I prefer the smaller protected beaches rather than the big exposed beaches. Its usually easier to find some shade on the smaller coves.