Get the Elixir low B strings and ditch the G strings you have if you bought that many sets. Widen the nut or replace it, and set up the bass for the new string tension. This should get you going. Drop C# is well within the range of a standard tuned 4 string so this should work fine.
This is what I'm leaning towards. If it works it'll be mint.
I'll try an action raise anyway but I'll order the extra string and see how I go!