Including an extra bass string

Hi everyone, I've just entered the world of 4 equidistant strings. As I didn't have any spare high "d" strings (or guitar "e" or "B") I went the opposite way and added a guitar low "E" string to the bass side - tuned to D2; an octave lower than the usual bass string.

So my tuning is D2, D3, A4, D4 which gives a really majestic rumble, especially for playing Christmas carols. I've also experimented with tuning the D3 to an A3 which is also very nice.

Does anyone else tune to give extra bass or is there any documentation or resources for tuning this way?

Thanks :)