I'd just make one. Pitch the tent on top of a builder's tarp. Draw round it and then cut out about 10cm inside the line. Or if that's too much DIY, buy a ready-made tarp that's a bit too big and then tuck/fold the edges/corners in.
A day of all things motorhome and campervan. The show is held both in the main indoor arena and across the grounds. Catering, hot drinks and food options are available. Easy access to the site and free parking included. Win one of five pairs of day tickets