A couple of summers ago I chatted with a sixty-something couple I bumped into on a local bike trail about their first RAGBRAI experience which was only a few weeks in the past at that point. They used the Register truck as their “charter”, they loved it, and they planned to do it again! The Register truck is a fine way to do this ride and you don’t have to be young to use it. You will find showers, food, drink, bathrooms, camping space, and entertainment easily enough.
I’m less sure about phone charging but two or three 10,000 mAhr phone charging batteries are small, light, and should be enough to get you through a week. You can also be one of those people who huddle around every outside power outlet at every public building in every town. If you were to ride over to the RV village with its sea of motorhomes with generators running you could ask nicely and possibly charge from one of their outdoor outlets. To be honest if I came back to the MH after dinner and found someone plugged into my outlet I would not be upset at all. However, if you haven’t collected your stuff by the next morning when we are ready to pull out I’ll just unplug you and drive off so do take care to gather your belongings before that happens!