the suspension trailer I made in post #38 was deemed a failure because the overhead required to make a suspension system added considerably to the weight. Also, the intrinsic flex of the trailer bed was comparable to the suspension travel. Also the suspension compromised the wheels' lateral strength. Adopting a prebuilt suspension system from a bike might be a solution, but is probably overkill. The leaf spring idea mentioned above, is an idea worth considering, but could easily add too much weight. simply building a rigid trailer and suspending the load with some bungee cords is probably the easiest of all solutions.

I think it's a case of solving a problem that doesn't exist (I hate it when people say that.)

Instead I built another (number 4) rigid frame trailer, which has a perfect (for my purposes) geometry: 16" wheels with axles raised ~2" above chassis, makes a big difference in stability. Room for two large tubs. My personally favoured Universal joint hitch system.

It's pictured below as a beer train (front trailer). My orignal trailer (number 1) attaches to the rear. the universal joint approach makes these trains very easy to put together <- this is my 'construction tip', which I shall repeat ad nauseum.