Multiple TV's with Apple TV in one room and more than one ipad, will they interfere with eachother via airplay?

What are you trying to achieve?

You will need a WiFi network. In addition, you will run into issues initially setting up your ATV's without an internet connection.

With all of the above present, it is possible to get them to work.

Makes sense. You need wifi to allow data transfer. Bluetooth alone is not adequate.

When setting up the two TV's make sure you name each Apple TV a different name otherwise you could be embarrassed when it goes to the wrong monitor.

Given the critical need for you to look flawless, I would purchase 2 Apple Lightning to HDMI adapters and long HDMI cables as backups.

Getting Airplay to work in a home environment is ok but being on a exhibition floor with who knows what kinds of unpredictable radio interference present, I would count on having problems.

Could it work if you bring a wifi network? Yes.

If it were me, I would go the cable and adapter route. It is bulletproof and you can focus on the sales and not waste time excusing your technical difficulties.