Marc, I do chant work constantly. The best I can suggest is individually nudging unusually long syllables/words or using the note spacing tool after the fact to make adjustments. You can also decrease the default note spacing, which tends to yield better results by default.
As to Daniel’s point about tick barlines, personally I think that making them wider in all scenarios by default would actually be a good thing, since I’d guess they are most commonly used in chant anyway. I find I often nudge notes away from them on the right even mid system. (Just did this yesterday, in fact. They are so little that they are easy to miss, so giving them more space tends to look better.)
As for the ends of staves, I requested this a long time ago (see above). Every professionally published hymnal in my (extensive) collection moves tick and half barlines a few spaces away from the end of the stave. It is certainly very common modern practice too.
You can add dummy measures after you decide on the system breaks, and then hide the rests, but this is cumbersome, and it’s much easier to just fix it in InDesign or Affinity Publisher, which is what I do. I take every score I produce into AP to make all these little tweaks. Sadly, for this type of work it simply isn’t possible for me to go straight from dorico to print.