I think the point of what people are saying is you need to not be banked once your turn has begun. Not be leaning in. Not be leaning uphill. Not be leaning inside.
Now all that is so negative. What to do instead? And why?
1. You need to lean sideways towards the outside of the turn once it gets started. You will feel a pinch at your hip/waist area on the outside. You may also feel a stretch at the inside hip/waist area. Check inside in front of a mirror to see if your body has the flexibility to do this. Or try this: stand in the middle of a doorway with your right hip about 2 feet away from the door frame. Without moving your feet, lean over toward the doorframe so that your right shoulder and right hip rest against the wood. Feel that pinch on the left side? Feel the stretch on the right side? That's what you need to do (sort of - see #2) on snow. This is called angulation.
2. In order to be able to lean sideways effectively, you need that inside leg just a wee bit forward of the outside leg, and that inside hip and shoulder just a wee bit forward too. Turning your feet and legs more than your upper body as your turn progresses will make this happen; you don't have to think about inside half lead if you are already turning your feet/skis/legs more than your upper body; it's a by-product.
3. If you are facing more down the hill than your skis in medium radius turns, then you already do #2 and you have the inside half lead. Just focus on the leaning sideways out over the outside ski a bit more than you already do.
4. Why do this? To get your weight over the outside ski. The outside ski is the one that needs to be taking the pressure that builds up during the turn. That outside ski is edged to your foot's Big Toe Edge. That's the strong side of your foot. It needs to carry the load. The inside foot/ski is edged to the Little Toe Edge, which is your foot's weak side. You don't want too much weight/pressure on the inside foot and ski. If you focus much of your weight and the pressures of the turn over that little toe edge of that inside ski by banking, your outside ski may lose its grip and you'll probably fall on your shoulder.
4. Why drag the outside pole? Why aim for hands or shoulders "level" even if they don't make it all the way to true "level"? Because doing these drills usually brings about #2. Once you get the feel of having your outside ski bear most of your weight, you can forget about the pole dragging and shoulder leveling.
There are other reasons that can contribute to the tail washing at the end of a turn; we are just guessing that this is your primary issue. When do you get to ski? Are you able to ski these days?