Use a stainless steel water bottle (cleaning with vinegar or not). That metallic taste (which I've never noticed over use of several such bottles, as my kids lose them) should have no impact on some fine bourbon or other brown liquor.
You can also carry enough that way.
AS noted above, make sure they are packed in a sidecase or topcase, and not a tankbag; if it is accessible to the driver (rider), because it is not sealed in the bottle in which the booze was sold, it is considered carrying open alcohol and a violation of the law (in Illinois it's an 11-502, open liquor).
- Dan