The idea behind the Baritone is to be able to tune lower without using too heavy a string. I think with plain medium gauge strings (.013″ – .056″) the 2-1/2″ extra string length on your Baritone should carry the C to C tuning. Remember, some folks manage tuning that low with 25-1/2″ string length instruments.
I personally like our Baritone guitars tuned D to D (the standard tuning for these models) with medium strings and dropped tuned a little from there if desired. It’s also very versatile because with a capo at the second fret, it is instantly transformed into a 12 fret neck Long Dreadnought model at standard pitch!
The D’Addario heavy gauge strings for regular steel string acoustic guitars (.014″ – .059″) are a good choice for your application IF medium gauge strings feel too loose for you at the B to B tuning. Those strings are definitely too heavy for the D to D standard tuning we recommend, however at the C to C tuning they would be okay.
I think heavier ‘Baritone’ strings sound dull and thumpy, almost bass guitar like. This loses much of the beautiful, transparent, clear and resonant quality I’m trying to achieve with our Baritone model. Also, the nut slots and bridge slots would need opening up.
Too heavy a string gauge tuned to an overly high a pitch will void the warranty for structural damage reasons.