An outfit called Southeast Publications prints the RV Park site maps - the 'placemats' that you are given when you first book into an RV Park. Those are provided free to the RV Park, paid for by the local advertising displayed on the placemat.
The Sales Rep can travel wherever he wants, get a two-week complimentary site, while he sells local advertising to be printed on the host RV Park's 'placemat'.
It's commissioned sales, but it fits what you described: travel, low investment, low overhead and your wife can be actively involved.
Details are here: http://www.southeastpublications.com/index.php/careers
No, I do not work for them. I met a fellow FT-er at Amazon Murfreesboro during their peak who got me thinking, though. A friend of his has been doing this for years and now earns a comfortable living.
Just a thought.