Some tuning questions - Sport Plus 2Rs, tire pressure, etc.

Current I'm trying to do a street-custom build out of the Bruckell Bastion 6.5 GT and am struggling with tire issues. I'm using Luuks Tire Thermals and Wear Mod for reference.

The first thing I've noticed with the Bastion and this mod is that on both ends, the center of the tread heats up much faster than the shoulders, as if the tires are overinflated. Dropping tire pressures all the way down to 28psi front/30 rear, which would likely cause a blowout risk IRL with a car of this size and weight, seems to slightly reduce the disparity in the rear but has fairly minimal effect on the front. The UI app that comes with this mod also shows where the contact patch is currently centered, and it seems very stuck on the middle ring of the tire, which could explain some of this. Taking the front camber all the way up to -25% will show the contact patch moving to the inner shoulder of the outside front tire in hard corners, indicating that the stock suspension has some fairly nice camber recovery and/or well-set caster, but otherwise, that contact patch indicator still seems locked to the middle ring.

I also experimented with switching to Sport Plus 2R (305/30R20) tires from the stock Sport type (305/35R20). Cornering speed actually seemed to decrease and the behavior of the car went down the toilet. Taking the car to the Gridmap skid pad, with tire pressure and camber values reset to default, showed that the grip barely increased (talking around 0.03g benefit here) from Sport to SP2R but the behavior change was not as severe as I believed. (It's very difficult to measure the Bastion's maximum grip anyway as it seems to have about 0.05g or more worth of grip locked behind weight transfer, which can be accessed while maneuvering but not maintained by any means.)