The contact area of the container is 0.4m x 0.4m = 0.16m2. If 5000N can be spread over 1m2 then a reduced force of 5000 x 0.16 = 800N would be permitted over 0.16m2.

Using the conversion factor of g=10m/s2, which means the same as 10N = 1kg, 800N is 80kg,