The well drilling folks up here have taken to using a polyetheyelene (sp) mat about 1/2" thick to make a runway for their rigs. They still leave a depressed "rut" but it is far less evident than 6" deep truck tracks. Stuff comes in 4 8 foot sheets. Fairly pricey but doesn't rot or absorb water. Seems like a few sheets would make good turning points for a mini.
http://www.duradeckmats.com/?gclid=CNSws7Lo45QCFQplHgodyUs7Qw
http://www.duradeckmats.com/?gclid=CNSws7Lo45QCFQplHgodyUs7Qw