I think you flex looks adequate for more wheeling. Because the trucks are so light in the back it's difficult to get a lot of flex in the springs without going so soft that you lose stability.
This is my problem with my 88. When i'm loaded light for trail riding it flexes alright but when loaded heavier for Rubicon or camping/wheeling trips it's flexes great. hahaha I think without going to a 4 link rear it's going to be hard to tune the leaves in for the amount of flex you're after.
