messed up susp. probably bent frame

[RBS14]

So after i installed my coilovers i drove the car for a couple days and then decided for sh!ts and giggles i'd measure from the center of each wheel to the top of the fender to check my ride hight. All came out fine except my driver-side rear wheel. It was 1/2 inch lower than the others respectively.

My car was hit on that corner earlier in its life. I inspected the subframe and it appears to be perfect. All suspension arms are the same length and none appera to be bent. so the only thing i can figure is that the frame was bent in the prior crash and they bolted on new stuff and left the frame somewhat bent and figured it was good enough.

I'm having the car put on a frame rack next week to see how bad it is and hopefully pulled.

Here are my questions:

Is it safe to just raise up that corner of the car via my coilovers if they can't fix the frame?

Is it safe/recommended to make some steel spacers to put inbetween the left side of the subframe only and frame then have the car corner balanced?

Neither of these ideas seem intuitively like good ideas to me but i just thought i'd throw it out there. I don't know why but they just don't seem like good ideas, but they ran through my head so i figured i'd ask.

Thanks to all who help in advance!!!