It's been a long time since I looked at my rear brake lines, but if I recall, and based on your photos, it's routed along the upper control arm normally, so they really shouldn't be pulled any as the axle droops, the radius remains the same.
I do know that I'm still running factory brake lines all around on a 4" savvy with no problems, but I relocated the fronts lower on the frame. I don't think I did anything special with the rears whatsoever. Your parking brake cable looks snug though.
