even a small indoor Supercross track would be too big for BMX racing!
i would guess that an outdoor track would be much bigger & totally unsuitable for racing as such
however, there would likely be plenty of room for camping, little or no noise restrictions & possibly some sections of the track with Massive jumps (hopefully close to the carpark/camping area) that could be used for a dirt jumping competition
you'd need to go & do a decent recce on it really