Devyn, you're doing awesome. There may be those things that are generally recommended, like not dropping intensity, but you do what you need to do. If you are constantly lifting into severe pain, it makes lifting no fun and arguably not safe depending on the pain. If a deload makes things physically and mentally better, it is the right choice. A deload would also play into losing some weight if you wanted to do a cut right now, or even adjusting your calories closer to maintenance.
You're absolutely right on SRA (at least to my understanding). To me it's not that SRA ever goes away, but like you said - the comparison to between novice and advanced lifter is definitely different. The former is a much more vertical adaptation rate line on a chart (assuming up is higher ), and it is very easy to describe since minimal complexity results in adaptation over a very short period of time. As that adaptation line becomes more horizontal, the time between adaptation becomes longer, higher stress needs to be introduced in regards to volume and intensity, and as you mentioned perfectly, fatigue is introduced and needs to be managed in addition to recovery.
Regarding SLDL and DL, I was just suggesting swapping the day they are on. SLDL would still be medium intensity and DL high intensity. The thought here (and it's not my own, I've seen it on the boards here) is that after doing 5x5 heavy squats and 5x5 heavy bench, you may just be drained for doing 1x5 heavy deads. By moving them to Friday, and even putting them first, you are fresh for this potentially very heavy pull. Being only 1 set should make it less of an impact on your medium squats and bench alternative. I only brought it up because you seemed disappointed about deads on your heavy day.