I just installed a Level Master bubble level on my trailer to go with my Andersen levelers. Since I was not interested in drilling holes in the thin fiberglass I did it another way using 3M Extreme outdoor double sided mounting tape. First I cut out two pieces of 1/8" by 2 3/4" by 2 3/4" aluminum. I drilled and tapped 2 6x32 holes in each piece. Four very short 6x32 screws were used to secure the bubble level to the aluminum. Two strips of the tape were used on each piece of aluminum. The level was carefully mounted. That is powerful tape so you sure need to get it in the right place. There is a little adjustment room with the screws.

