Tho I dont have a RRR, but to my understanding, your camber and toe in settings seem a little too aggressive for the track you are running. Unless its super high bite surface, or else too much toe-in can cause unstable action during take-off and low-speed movement, like the cases you described. You can also check the rear sway bar setting. Hope this may help.
The camber is set so the tyres wear evenly. The toe of 3* is to try and gain some rear traction. There is a LOT of camber change on this car through its suspension travel. Makes it hard to use the camber you want with foam tyres.
Should i be looking at the front end of the car instead? And try to reduce steering/traction at that end to balance out the car?
The track is really bumpy and all cracked up. Not much traction and a lot of tyre wear with 37 rears. I wouldn't like to go any softer. They wouldn't last 10 minutes.