I'm using the method I saw in a video of a brewery filling kegs (via a manifold, believe it was a MoreBeer video).
Sanitize receiving kegs and purge O2.
Connect a QD to the gas post that has one end in a container of Starsan (no fitting on that end) to create an airlock.
Connect liquid post on keg to beer out fitting on fermenter.
Push beer as needed from fermenter to serving keg.
Watch the line from the gas post and stop filling when you see foam coming out of that fitting. Just be sure you're seeing beer foam (not liquid) and not sanitizer foam.
I used this method the past couple of keg fillings with great success. It's also less complicated than using spunding valves or other configurations. Since most of us fully sanitize our serving kegs as part of the cleaning process (or at least I do), including running Starsan through the liquid post/dip tube, doing this right before filling is adding work that's not needed. Provided you keep the keg pressurized from when you add the sanitizer until you're ready to fill it. I do push the sanitizer out of the keg, until it's empty of liquid during that process. At most, it has some Starsan foam.
Since I'm putting part of the batches into serving keg (they are leaving fermenter fully carbonated) and canning the rest, it doesn't matter to me if I don't get a 100% full keg. If it's a pint lower than it could have been, it's not the end of the world. Especially since I'm not extracting the final .6 gallons in the conical due to how far the racking arm reaches.
IME, the simpler the setup you have, the less chance you have of something going sideways. Plus less items need to be cleaned after use (or taken apart and then cleaned).