Thank you for all the answers! The solution that best suits my situation is overriding the script.padding, what Vaughan suggested. I find the staccatos to be too close to notes as well, so having it affect all articulations doesn't seem like a problem (at least at the moment). As Lukas pointed out, dashdash = \tweak padding #0.5 \tenuto does not work in my version of Lilypond. (I'm a bit hesitant to spend my energy on updates, as my old computer might fall apart soon.)
Erika
