May be fine if you're a minimalist camper. Would be ideal if doing off road/green laning mixed in. Guess it would depends on the obvious things like distance you're planning to ride/time in saddle, plus how much gear you need, plus how confortable your packs are. When I use to go Mtbing, I used a modern Camelback, but always found my back was too warm.
My audax/winter bike (higher mileage bike) has everything I need hanging from it somewhere - saddle bags, pumps, lights, tools etc.....whereas I fill my jersey pockets and a small micro saddle bag on the summer bike - helmet light, Co2....
Load on bike or Load on rider?