OK, backpacking as in a romp around Europe during your gap year before college.
I wouldn't consider a hard case (Pelican). Likely overkill and its heavy and volume invariant. I've used an insert (mine by Mountainsmith) along with padding of various kinds and plastic bags and silica gel. Used that for actual wilderness backpacking as well as roaming around eastern Europe.
The plastic bags and silica gel must be used in concert, and I wouldn't consider them optional. You never intend to soak your pack in a rainstorm or "river incident" (don't ask
I tend to be over-cautious...other than the padding of the insert, I used additional padding around gear. You don't necessarily want to be carrying extra stuff (dedicated camera padding), so I used socks, underwear (clean), thin shirts,...you get the idea.
It should be obvious, but try to locate the camera centrally in the pack, or above the bottom. Dropping your pack on the ground is a natural habit. I'm not saying you'll throw it on the ground, but the standard "plop". Clearly don't want your gear right at the bottom, even with the insert/padding.
I think silica packs are important. If possible, recharge/replace them every so often. How often depends on how wet you get, weather, humidity, etc. Someone on this forum will know how long gel packs last. I think I tried
to change or recharge every week or so. Have no idea if that was right. I just needed to address the mental image of fungus proliferating in the dark, damp, warm, stifling environment of my pack. My FE2, 35/2.8, and a zoom lens all made it just fine through a month or so of summertime roaming around Bulgaria and adjacent countries. It was hot and often humid, and I visited a lot of caves (one reason for my visit).
And then there's the way you treat your film while packing....