It would definitely be a job for a professional restoration type company. Contact one in your area and ask questions.
I would definitely inquire on not just odor removal, but a total cleaning; walls fabrics etc.
They have the proper proven equipment and will guarantee their results, so if an additional cleaning is necessary they won't re-charge.
I think going that route, you will have success. If you are getting a good coach, for a good price the price of a professional cleaning will be worth the money spent. Perhaps call, get the price of the professional cleaning and negotiate all or perhaps half/split the cost off the price of the coach? Good luck with it!
Let us know what you decide to do!!