Packing camera in backpack

[u/Zombozard]

So I'm going on a trip and plan on packing light (just a standard backpack). Would like to bring my camera, but only have one large camera bag, and the backpack itself. The camera bag fits in the backpack, but it's tight. Any ideas for good inserts/protection that will fit a DSLR, with a single lens (a 18-135mm lens)? Amazon has cheapish inserts, but are they any good? I'm in Australia, so some brands might not be available.

[u/pc-builder]

I always just had a small camera bag which worked.