I have used auto-level on my trailer when I was on a grass site. But I retracted the slides first as this was suggested by the Cedar Creek tech, when I was at the international FROG rally a couple of years ago.
I had extended the trailer's hydraulic rams to lift a wheel and tire off of the ground at the rally, for me to change out. Cedar Creek had provided a new wheel and tire for me to replace a defective wheel on my trailer. When I was done the tech simply pushed the auto-level for me and the trailer levelled it's self.
2016 34RL CC; 2008 Ram Mega Cab 2500HD, 6.7L, 68RFE 6 speed, 4X4, Smarty S67, TDR 135K+miles