You don't have to write the I and J separately, if you have easy access to IJ/ij:

    U+0132 LATIN CAPITAL LIGATURE IJ
    U+0133 LATIN SMALL LIGATURE IJ

(On the EurKEY layout[1] this is as easy as AltGr + k)

[1]: https://eurkey.steffen.bruentjen.eu/