I'm not sure I understand why youre asking the question, when you answered it in your own post.
If you just want low tunings, get a baritone or detune another 6.
As standard a baritone is tuned 2.5 steps lower than a normal 6.
As standard an 8 has an additional B and F#, so the lowest string is considerably lower. Also, if the 8 is baritone scale (26.5 or 27), that doesnt cut it for the f#, imo. Not nearly long enough. 30" is where it should be, 28 at the very least.