This is not meant to offend anyone who lives in a mobile home...I know perfectly respectable people who live in trailers. (Of course, they have ambition to move into other, more substantial housing.) But if you live in a trailer and your idea of "adding on" to your home involves setting another trailer next to yours and opening the doors between them to join them together, I think you should seal the joint with duct tape in order to maintain to level of integrity of the structure.
And remember: nothing screams "class" like a doublewide with an awning built over it.