An interesting article, and the funnel analogy is very apt (except the blue portion should be narrower). However, I believe Peter missed the boat on art fairs. The photo shown of the display at the art fair is very atypical. In virtually all art fairs you are given a 10'x10' space (sometimes with extra behind to store inventory, but not always - some shows will I've you the option to buy larger spaces). In this space you need to put a canopy (which hopefully will be waterproof (light ezup types are not waterproof). You then need to display your framed art on those walls to attract the public to come in. You also need to have unframed work available - most purchases will be of unframed pieces. And if you don't have space behind you also need to store excess inventory, and all the other bits and pieces needed to run a business. Obviously you need to have some space between framed pieces, but you can't go overboard, because of the limited space available.
Before you get to this stage you need to get juried into the show, which is easier said than done. Images you use to jury in may often not be what people will buy.