At RVIA sanctioned shows, like Tampa, Hershey, Pomona and many, many smaller shows, the RV Manufacturers pay for the space and invite their dealers to be there.
The units at the show are generally already floored (owned) by the dealers. The manufacturers incentivize the dealers to move the show units during the show.
Factory orders for the RV of your dreams, the one with just the options you want and none that you don't want are generally taken at shows "at show pricing".
For those just starting their research, the shows can be invaluable. Take a camera, a tape measure and a notebook. Plan to grab brochures on only those that are candidates for you. Circle the floor plans you really like and write the show price in the circle.
For those who have already done their research and are ready to buy, while great deals can happen at anytime anywhere, truly great deals can be had at shows as well. Dealers do not want to bring these units to their lots. They want to sell them at the show. When dealers move all their show units at a show, they need to reorder right away. Manufacturers like this. This is why they incentivize the dealers to move the show product (or factory ordered units).
Have fun in Tampa - it's a great show.