JT's Strong Arm Stabilizers and Insulated Trailer

Mine has an enclosed belly with the corrugated plastic. My frame is I- beam construction and I was able to bolt through the outside edge of the beam. I just cut away small squares of the under belly material where the brackets were. You could just bolt right through the material as well. It will compress to the frame when the bolts are tightened so the brackets will be tight. You can use self tapping bolts if you are unable to access where the nuts are needed (ie square tube frame)