Ok, I get it now.
Sorry it was late when I replied last night.
Some important definitions.....
Display board= Pretty thing used to win best painted in a tournie.
Movement Tray= In game aid more commonly used in wfb that allow a unit to be moved as a whole.
Moving Tray= Cookie/cafeteria trays used to place casualties and move models between tables at tournies.
So yeah. A carefully designed display board could double as a moving tray and contain movement trays also.
Your idea, however, sounds like it would give you a hernia lugging it between tables for a few days.
Best leave it in the car and bring it out for judging/viewing periods and use seperate moving trays throughout the day.
I think i've got it now.
Hope this helped?