Undefined AR class module for Marshal

When I do Marshal.load, and the data includes AR classes, it gives me an
undefined class/module error along with the AR class name.

If I require the model files right before calling Marshal.load, it will
work fine. I don’t want to be requiring the AR models everytime I call
Marshal.load.

Whats confusing is that if I do any kind of AR actions/methods (i.e.
Model.find), it will work fine without having to require the models
again.

Why do I have to re-require the AR models if I Marshal.load the AR
object?

This consistently happens to me still with unmarshalling data.

Is there any work around to this?