My weekend project: Mobile benchrest

My 100 yard shooting range is in the middle of a field, so i needed a mobile benchrest.
The frame is all "recycled" steel i found here and there around the farm.
The benchtop is made out of two layers of 20mm MDF, one layer inside the frame.
Adjustable supports in all three corners to make it as stable as possible.
I might add some more weight to it later, but it seems pretty sturdy when its leveled and the wheels are off the ground.