I don't think anyone will fall for a claim of back injury in a landing that did not damage the a/c or require a heavy check. The g loadings for these are remarkably low, way way below what could be seen as culpable, let alone what is usually believed to injure people. My company had a heavy landing in a 320 that was witin .1 or .2 g of requiring a main landing gear change. No one was injured. The a/c was grounded for some considerable time while Airbus was consulted. istr they hadn't had one that hard before and weren't entirely sure what to do about it.
I think you're on very thin ice here.