Loop-outs aren't hard and the stepping off comes naturally, in my experience. And sure, it makes sense to practice them before wheelies, but that's also the natural course of events - you'll almost definitely overdo it a few times before you'll catch the balance point.
Regarding the saddle getting in the way - it may depend also on your bike's geometry which determines how high can you lift the front before looping out. In my experience, a wide saddle didn't cause problems ejecting myself. At the loop out point the saddle is pointing nose up and you are moving away from it to the rear which results in an almost upward movement relative to the saddle instead of rearward as it would be if the saddle was level.
I was pretty decent at wheelies in my adolescence, I could do over 100 meters on a coaster brake bike. Later I gradually lost my interest in it and haven't practiced it anymore.
One thing I learned from wheelies on coaster brakes: as there is close to a half crank turn between engaging the brake and engaging the freehub, you don't use brake for balance, and as a result, speed tends to gradually build up. And looping out at speed is not a fun thing - you must be prepared to let the bike go, otherwise it may carry enough momentum to drag you down facefirst as your feet cannot keep up with the speed they are suddenly subjected to.