I just completed a project I have intended on doing for over a year now. I purchased a carport from Carolina Carports and couldn't be happier. The install took less than four hours and the project was completed when scheduled. The crew show'd up on time and did an excellent job.
Just remember, ALWAYS build bigger than you think you will need. I purchased an 18' x 41' x 12' cover in the event I wanted to acquire a 5th wheel somewhere down the line. It is wide enough to open the deep slides on my Coachman Freedom Express and still have room to walk around under the cover.
Here is a link to the compilation of photos showing the process.