An alternative, but maybe not best for the OP yet:
I've got a Hipshot DoubleShot Xtender on my main bass, a 4 string. So a low D or even a C are just a flip of the lever away. I use it all the time. My 5 string has been gathering dust ever since, I don't see using it for anything but fun any more. No low B, but so what, how often do you need that? And it can always be tuned to the B instead of C.
BUT, if you still don't have a handle on where all the notes are all one of those might do is confuse you, because it changes the notes on the E string. I'd really work on that before anything else. But it isn't that hard to learn to play in DADG or CADG once you have a clue; get a clue first.
I've got a single Xtender on my fretless and a few other basses, too. Just a happy customer.
And no, they don't cause your strings to break. I've gone years on an E string using the drop function a dozen times a gig plus numerous more practices. I'll tune the E every set, but tune the dropped notes only when needed, they hold tune pretty darned well.