Check out the thread linked below - scroll down to the bottom and you'll see a link to Linda Z's blog with the conversion formula for using rice vinegar in recipes that normally require 5% vinegar.

Here is a link that might be useful: Canning Pickled Ginger Thread

Since you are already using a 1:1 brine mix which is the lowest recommended there is a potential risk with shelf time (ph rises with time). If it were me I'd go to at least a 2:1 ratio.

Dave