I wouldn’t worry too much about gapping all the way thru the driver, as the driver is a club that most people will want to hit as far as possible. I would focus on how far you hit the 3 wood and consider what you need to fill the gap between the 3 wood and the longest iron. You are right on in considering the 3h KE4 Tour Hybrid or something similar, with a loft of 19 degrees. The MMB-17 4 iron is 24 degrees, so based on the lofts, you would have a 4 degree loft gap between the 3 wood and the hybrid, then a 5 degree loft gap between the hybrid and the 4 iron. This could work, but you will probably need to take the time to hit them to see if the gap is what you want. The length you make the clubs, along with the overall weight will also have an effect. Finding the right length to make the hybrid is key. If the 3 wood is 43″, for instance, and the 4 iron is say 38.5″, the hybrid would probably need to be 40.5″. At 40.5″ with a 80 gram shaft and a 50 gram grip, the swing weight would be around D1. Unfortunately, the only way to know for sure is to try the hybrid and see if it does the trick. It may be that an 18 degree 5 wood or hybrid and a 21 degree hybrid, giving you a 3 degree gap between all the clubs (3w-15, 5w-18, 21-Hy, 24-4i) would work better. This adds an additional club and may require you to give up another one somewhere in the set, but only if you prefer to play using 14 clubs. Also, if you mainly play one course, you should think about shots you may regularly have and what club(s) you may need to add to better execute those distance shots. If you play a lot of courses, you may want to have several options. Have the 19 deg. 3 hybrid, but also have the 5 wood and the 21 degree hybrid and set up your bag based on what you feel will be best for the course and conditions for any particular round. Personally, I have a 15 degree 3w, 18 degree 5 wood, 19 degree hy, 21 degree 3 iron, 23 degree 4 iron … Depending on the wind conditions, course conditions and how I feel am striking it, I will choose what I feel the most comfortable with for that particular day. More information than you wanted, I know, but it is important to have choices and to know exactly what the trajectory is and how far you hit each club.