Trying to Lower my SPL

This week, for kicks, I decided to take one workout to see if I could lower my SPL for 25y to as low as I can get it.
My best SPL before this was 12 strokes for 25y. I was determined to do better, but also figure out what I needed to do to actually get a low SPL.
On my first 2 tries, I hit 11 SPL. Then I hit 10 SPL and held that for 4 lengths, and then ping ponged between 11 and 10 SPL as I got tired.
Some thoughts on getting to a lower SPL:
1. For this exercise, I had to lower my tempo a great deal. This increased my glide time for each stroke.
2. At higher tempos, I try to ride my speed curve, meaning that I try not to let my speed drop too far as my current stroke ends, before my next stroke picks up the acceleration again. But for this exercise, I let myself get further down the deceleration part of the curve after my current stroke ends, and I let myself maximize my glide before my next stroke begins. This minimizes my stroke count and maximizes the distance I glide for each stroke.
3. I found that I for each stroke, I had to really stroke back with great force, as well as shooting the lead hand forward at the same time. This is to maximize the distance I cover with each stroke. However, I tried to do so with proper form, not throwing water with my rear hand backward, really engaging the core in my stroke for more energy, and using my kick to give my rotating hip extra energy.
4. My bodyline needed to be perfect. It needed to be straight and extremely streamlined, so that on each glide I would minimize deceleration due to body drag.
5. My body also needed to be stable, and not be rocking back and forth during a stroke and glide. Any kind of extra movement creates drag.
6. I need to be as relaxed as possible and just let my body glide in between strokes. A tense body creates all sorts of disruptions leading to more drag in the water. Besides, it also wastes energy.
In some ways, I felt like I was cheating; I would just stroke once and then ride the glide for as long as possible. In thinking more about this, I think this is a beginning to a set of exercises to increase efficiency in the water. I had to go through this first to figure out what it would take to get to 10 SPL. What did I need to do to my body? My stroke? How much force do I need to generate with each stroke?
Obviously to maintain my SPL at a higher tempo, I would have to be moving faster and farther with each stroke or else my increased tempo would add a stroke before I would cover the same amount of distance per stroke, at a lower tempo. This means I have to do all those items I noted above, but just at a higher rate and with more forward acceleration and momentum.
My next task is to slowly increase my tempo and seeing if I can still maintain my 10 SPL, and then find my breakpoint tempo-wise where I cannot maintain 10 SPL no matter what I do. This is a critical point at which I’ll have to practice a lot.