Do you used a water level to level a 12' by 60' trailer house?

Use a garden hose that is long enough to reach three corners of the trailer house from the fourth corner. Fill the hose with enough water so that the water can be seen from both ends of the hose (a short piece of clear tubing securely connected to either end of the hose would be helpful).

Start at the first corner and hold the hose so that the water is level with the the bottom of the frame (or any feature that is at a common level at all parts of the trailer house).

Secure the hose in place (or have one person hold it) and take the other end of the hose to the other three corners. Note the height of the water at the other three corners.

Adjust each corner of the trailer house until the water is at the same level at all four corners.