I have always tuned a full tone low and put a capo on the 2nd fret which comes off only to change strings. I've never eft a set of strings on for two years. They must be pretty dead by the time you change them. Except for the capo (Paige) that stays on the 2nd fret, I've never been able to use a capo on a 12-string. It always pulls the strings outa tune.
Lead Belly tuned a lot lower than I do often two full steps. He also tuned his low E string course two octaves apart. The octave E was the same pitch as the open first string. (That's the way his guitar was tuned when he died. I often wonder if he put that double octave E string on because it was all he had.)
Pete Seeger also tuned low and almost always dropped the 6th course a full tone (Drop D, but lower than D)