Are you comfortable drinking from a bottle while the bike is moving? You said "safer" - so I suspect perhaps you are not.
If you are not, I don't think the added weight of a Camelbak will be a huge burden. You aren't packing all of your gear there, are you? Just water/Gatorade? Don't go crazy with the storage, and it would be fine. You can always take it off at the rest stops to give your back a break.
If you are comfortable drinking while moving, for an organized ride with plenty of rest stops, I'd say 2 water bottles should be fine - even on a hot summer ride.
Only you can make that call, really.
2007 Seven ID8 - Bontrager InForm
2003 Klein Palomino - Terry Firefly (?)
2010 Seven Cafe Racer - Bontrager InForm
2008 Cervelo P2C - Adamo Prologue Saddle