In simplicity, Two things your body will need. 1- the ability to feed itself from stored fuel and food you introduce over several hours. 2- the ability to sustain the riding position, continuous motion and sustained force for several hours. If your training and adaption enables you to do that, then your plan is good to go. If you can't do either on the two, then you need to include some training rides during the "off weeks" to train those functions.