The RPG preload collar is a good thing. I would keep it. Helps with off-roading and prevents the front from being bouncy. You need to get the ride height adjustment recalibrated for the Live shocks, do this first before removing and try it out. But I would also change how the live wire is attached as it shouldn’t be zip tied to the coilover (looks tight). Measure both the rear and front to the top of the flair. How much difference is there actually?
If you want a rake look, You will be better off upgrading the rear to either ICONs or Deavers +3 to raise the rear instead. The rear on these trucks suck in their stock form.