Try some high tension strings from Newtone Strings.
I had two basses in Drop C Standard for a good 3 years, using 45-105 gauge strings, with a similar action and tension to standard tuning!
The only downside to higher tension is that they often don't go up to Standard too well. You obviously have to set the neck up to accomodate them.
Remember that it's the core of the string that determines tension, not really the size/guage of the outer winding.
Give Malcolm a call, tell him your tuning, and they'll sort something out for you....usually for a similar price to Elites/Rotos
Si