I used to have the same problems with any Ibanez 5- or 6-string bass, too, with the narrow spacing. Then I tried a BTB, and loved it. I believe most, if not all, BTBs are 18mm or wider for spacing.
I also had a Lakland 55-02 that was 19mm, I believe, and it was great.
I also had a Lakland 55-02 that was 19mm, I believe, and it was great.