I’ve been thinking about possibilities for retuning a 6 string bass for tapping. Aside from straight 5ths or inverted 5ths, how about strings 3-6 as inverted 5ths (DAEB or BF#C#G# ascending) and strings 1 and 2 in 4ths (DG or AD ascending)? Basically, the goal is to enable 2 hand bass Stick-like lines and bass chording with rhythm accompaniment or some melody. Obviously, a bit of setup work and nut cutting would be needed. Or is it just not worth it for less than 8 strings? Mostly just a thought exercise at this point.

Just an idea: take a look at Jacob Collier's guitar tuning. It's a 5-string concept but it should work also for a 6 string.

Here's a link: https://www.ultimate-guitar.com/news/gear/jacob_collier_explains_advantages_of_5-string_guitars_i_wanted_to_find_my_own_way.html