I tried the large OMM bag but the water bottle began to pull away as its stitched to a mesh pocket.

I currently have a Lowe lightflight aqua thing. The water bottle (standard) fits in the middle of your back. It also has mesh pockets u derived a hunger cord to hold gels. Not sure how well the relatively flimsy bungees will hold up. It is made up of 2 pockets to separate gear but they are interconnected meaning you could get a full size map in there al either not 'to hand'.

I looked at the new Inov8 race elite 3.5 but it uses a proprietary bottle and no little mesh pockets