Camber. Years ago I found a graph that showed our rear camber changes under compression. After poking around several times in the years since to find that info, I kinda gave up. I vaguely recalled deciding that the graph indicated a rule of thumb for us of -1deg of camber for every inch of rear compression. Recall that our old springs would compress only about 1.5". Obviously our new springs can compress more. The way mine are set up they could prob compress 3".
This assumes horiz trailing arms, and ours are very close to horiz. If the trailing arms are compressed or unloaded a fair amount, the camber change increases. So camber gain from 2-3" of compression is more then it is from 0-1" of compression.
Tonight I found an old post by someone that seems to know what he’s talking about. He says -0.9deg of camber for each 1" of compression, and that this is pretty accurate for 3" of vertical movement, call it 1.5" of compression and 1.5" of unloading. So if you have -3 rear camber, under an inch of compression you can expect it to become -3.9. Contrast that to the front that gains no camber under compression.
Toe. The same post talked about toe. Folks told me for years that our rear end toes in under compression. But I tried to measure it once and the way I measure toe is super accurate because I shoot a laser beam forward towards a reference that multiplies change by 6x. When a toe problem is multiple by 6, you can see it really easily. I moved the car up and down a bit but could not spot toe changing. This guy says that our car changes total toe 1/16" (1.6mm) under 3" of compression. That’s 0.8mm of toe change on each wheel with 3" of suspension travel. Geeze, no wonder I couldn’t spot the change.