Yes, your parameters seem right to me. I also take about 30 degree dive, in idle, and try to release around 1 mile or so (when the red light appears), which falls short of the target. 1,2 kilometers might be better. If there is actually no CCIP in play, then I just will have to do some better calculation indeed!
In 1.2.16 the pipper really behaves like in CCIP mode: it moves up when you are nearing the target, when it is over the target the red light appears and you release.