A lot of these tournament sites are too small to hold a pickup boat. At a large site like River Bend in Oklahoma, there is space for a second boat, and it really helps to keep the round moving along if a skier falls on the north side of the course.
http://maps.google.com/maps?q=oklahoma+city,+ok&hl=en&ll=35.523477,-97.385516&spn=0.004925,0.010568&sll=37.0625,-95.677068&sspn=38.826758,86.572266&t=h&z=17