mom wants solar on her class C.... i need to do this cheap.

Hi,

I would go with the 3 panels. No telling if "Mom" will want to add an inverter in the future, and if she does consumption will be much greater. There is no such thing as too much solar, especially during the short winter days.

For example, one hour of a 300 watt inverter would consume as much as all the current parasitic loads.