Field Perimeter on Carpet

Has anyone here set up their field perimeter on a carpeted surface? We are trying to do so, but the perimeter is sinking into the carpet, making the holes at the bottom of the perimeter inaccessible. We were thinking of putting wood blocks under the perimeter to raise it, but worried that this may cause too much of a difference between it and the fields at competition.
Any tips?

Thanks,
Andrew

i think if you use 1/4 or 1/8 inch plywood you should be fine remember in the vex manual it says that the field has a tolerance of + or - one inch