I've only used my toy hauler a few times now and I've tied the X3 down three different ways. I don't have access to the bottom side of the toy hauler and the X3 is a tight fit. I think I've settled on running the straps underneath the X3 in opposing directions in a criss-cross pattern (if that makes any sense). I'm tying off the RF A-arm to the LR tiedown, the RR radius rod to the LF tiedown and so forth. I drove about 180 miles on my last trip with no issues. It's doesn't provide much down force, but it kept it centered. I know toy haulers and X3s vary in size and layout. But, I'm curious how everyone else tie theirs down?