I have a 27" scale Legator Ninja 7 string and am tuning it to drop G (D standard w/ a low G). I currently have D'Addario NYXL's on it (11-64 gauge). I like the feel of this gauge, but the low string goes out of tune too much for my liking. I was thinking of getting Ernie Ball Power Slinkies (11-48) and throwing on a low 70, and wanted a second opinion. As a reference, on my 25.5 scale Ibanez RG, I tune to drop A# and use Ernie Ball Not Even Slinkies (12-56) and replace the 56 with a 60. Any help would be appreciated. Thanks!
Buy an 8-string

You could look at the string gauges for 8-stringed guitars and see what they are like. Then again, D standard isn't too weird. Have a look at what is normal for the low F# on an 8. I kind of suck at string gauges, because I tune all my guitars in regular tuning with .10s or .11s
I do not want to have a signature anymore.