Contact a real estate attorney before you buy anyting in regards to this project. In some areas you can only put a mobile home on 5 acre lots. In some areas the home has to be a modular home and meet certain standards of construction before it can be moved unto a lot. You need to kow if the lot you buy you will be able to legally place a mobile home on it.
Then there is the issue of who pays for what inregards to connecting utilities. Please talk with an real estate attorney to help you through all phases of this, even the negotiations when purchasing the mobile home which can be fraught with minor complications which can cost you hundreds of dollars.
All the best,
Jeffrey Paeltz, SFR