What kind of tour, off road, road? You going with rack and panniers or framebag, bikepacking, etc?
MSR makes dromedary bags which are expensive but very durable, more so than the clear platypus bags. Both should last you a bunch of trips but the MSRs will typically last longer than the hard plastic type bags. You can try to lash the MSRs to the tops and outsides of bags if you're trying to avoid a camelback.
If it's a road tour, you can try using trek bat cages with hose clamps to the front fork legs (if you're not using a front rack) and something to tie the waterbottle down, string, bungee, etc. This isn't failsafe but does work. Cages fail, bumps, etc.. You can also get away with hose clamps and mounting water bottles under the downtube, better if you have fenders to keep the muck off..