Mobile Home Foundations
In the old days mobile homes where supported by concrete block piers and foundations were not an issue. In these days of modular homes, that is no longer the case.
Manufactured Home foundation standards are set by HUD and various state and local legislation and regulations. They are significantly different from place to place so it is hard to offer specific advice. The articles linked to below should provide some basic information to help with your search for specifics that apply to your local area.