For one thing, I was thinking about OAR and how it's used in final timing calculation. Here's how member sc544x4f150 corrected me on the HPTuners forum.
"You do want it as close to -1 as possible but it functions a lot different that what you suggested. It is a multiplier against the octane adjustment table then added to the borderline knock calculation. For example if the borderline knock tables output is 18*, octane adjustment tables output is -5, and the OAR is -.30 then your math would look like this: 18+(-.3X-5)=19.5* or 18+1.5=19.5*. So in that scenario the ECM adds 1.5 degrees to the borderline knock calculation. The other function of the OAR is to determine the LSPI limits. There is three LSPI tables: Low, Nominal, and High. These tables have the maximum air load the engine is allowed to reach based on RPM and manifold charge temperature. The Low table has lower load limits for lower octane fuels and the high has higher load limits for higher octane fuels. At an OAR of -1 the high table is weighted 100%, at an OAR of 0 the Nominal table is weighted 100%, and at an OAR of 1 the low table is weighted 100%. If your OAR is in between those numbers the ECM blends the tables together. Correct LSPI load limits is crucial to avoiding engine damage. I wouldn't trick the OAR just to get to -1. The correct way would be to increase your octane. Now for me I had OAR values all the way to -1 on 87 octane which would not support the load limits in my high LSPI table without preignition. To fix this I datalogged the areas of the borderline knock tables that had negative knock retard and added in timing to get my OAR to positive values and decreasing my load limits. When I'm injecting water-meth or have higher octane fuel in the tank the OAR goes more negative adding timing and increasing the load limits."
There's some really good insight there. Makes me rethink decreasing global timing.