Forum user @Diazo hasn't been around in almost a year, and this mod of his was sorely missed, so I've adopted it moving forward. Original thread is here: https://forum.kerbalspaceprogram.com/index.php?/topic/46647-13jun0417-automate-vertical-velocity-and-altitude-control/
Control your descent speed exactly and fine-tune it in 1 m/s increments.
This mod assumed you will use the Z key to control it. However, as this conflicts with the Set Throttle to Max command the mod is bound to no