Hopefully that solved your problem. But if it didn't, you will need a TALLER sight, which will make you point the barrel lower when the top of the front sight is even with the top of the rear sight, and therefore your shots will print lower than before. If you call CZ-USA, DW, and tell them your problem, as well as the length of your barrel, I'm sure they can suggest what height front sight to buy from them to get your shots printing on target.
No, I don't believe DW offers a 5" barrel. For ease in carrying, the 4" would be nice, and a little less bulky than a 6" barrel. And, with practice, you'll be able to be on target even at 50 yards plus.
If you're planning to do target shooting at 100 yards and more, I'd recommend going with a minimum of 6" barrel, but the 8" would handle those needs even better, and all the way out to 200 yards too. I've done a lot of silhouette (IHMSA) shooting, which is a sport with targets from 50 yards all the way out to 200 yards, with two of my DW's - one had a 10" barrel, and the other has an 8" one.
Let us know how things turn out.