Well honestly I tried putting myself into this position mentally, to figure out how I might react. Would I refuse and take the punishment on principle? Do I think I'm strong enough to go through solitary for an extended period of time without permanent damage mentally?

The problem for me is that in that scenario I would feel that my punishment is prison, the loss of freedom, and that I was not sentenced to either slave labor or solitary confinement, both of which I consider immoral under any condition.

There is technically a choice, but that seems pointlessly reductive. I'd have to ask you if you feel like someone given the choice between losing their leg or arm would then be more responsible for the decision than the person who cut the limb off?

I think there is some distinction to be made between free action and reaction. If you are put in a position where you are forced to make a choice, then its not just the individuals fault for the choice they make.