When I had my construction business I had two 16'-18' cargo trailers used as tool trailers for two different job sites.
 I tried single axle trailers at first but after a year and 88-90k miles myself and other drivers got tired of the beating. Both were a pain to get loaded without lots of bucking with the trucks rear suspension ....plus contents of the trailer would all be scattered in the floor. 
 Swapped them for two tandem axle cargo trailers and no worries about loading or balance or tools scattered about the trailer or the best part was no more beating the trucks on those long 300-400 miles runs..