I've found that the B11th is a great tuning for my 7-string Rick.....that's the tuning that Jerry Byrd used on his "Steelin' the Chimes" record.

I change it from time to time, to straight C6th.....ECAGEC# - C That gives you a real GREAT melody tuning with the bottom end providing for the sound you get like in Jerry Byrd's "Coconut Grove" intro.
and many others.

Either way, you can't go wrong.

You also can apply Jerry Byrd's diatonic tuning to those 7 strings. Don't limit yourself.

Jerry always got great sound/silky smoothness by using Gibson Black Diamond spanish guitar strings.....as follows:

1st, 2nd and 3rd strings are all SECOND
strings;
(#16 guage)

4th string is a 22 guage unwound/plain
spanish guitar 3rd string.

5th string is a flat wound 24#

6th string is a flat wound 28#

7th string is a flat wound 32#

All GIBSON......brand.

This string set-up allowed for all of the slanting, backward/forward....and a seamless continuity in sound without breaks in the sustained melody line.

Good Luck to you!

Is this what we're talking about?