Check out this post I made recently, wondering if it will help you?
Yes it’s a workaround, but I found it to be pretty fast. The gist is to change from percussion clef to a treble clef and back, which I have discovered “unlocks” the ability for a 5-line ‘percussion’ staff to act like a normal pitched staff temporarily, so you can set two notes at whatever distance you wish, and when you revert to perc clef, it preserves how you’ve set it.
Agree though in a future update I would like to see percussion staves and gliss markings with more flexibility, but for now this approach is working for me.
Also based on OP @ghfagan51 's original description, it sounds like something like this might be helpful?