Bill of Sale for a MH

Ok for those of you who may know…

I need help figuring out how to complete a MH deal when the owner has only a bill of sale and I intend on financing and reselling the home once I purchase it. Can I just sign a purchase agreement (like in Deals on Wheels) to buy and then sign a sales agreement (also in Deals on Wheels) to sell?

A more experienced person dealing in the sale of used mobile homes mentioned something briefly about him always selling using a bill of sale for business purposes so that he is not considered a retailer.

This makes me think that by selling using a bill of sale is a way someone like us investors can pass along ownership of the MH without ever recording our names as an owner. Kinda like when I remember buying old cars where the previous owner had given the current owner a title with his signature to release it and then he would never get it switched. Then I would sign it after buying it and that guy would never be known as an owner of the vehicle.