What's going on with 3500 lb axles?

You have to have the secret decoder ring to understand manufacturers’ spec sheets. For the Pod FR lists the unloaded total weight (UVW), the unloaded hitch weight (HW)  and the cargo carrying capacity (CCC). The sum of UVW and CCC equals axle capacity plus HW. IOW, the total fully loaded weight includes a fully loaded axel (3500#) and the unloaded hitch weight. Using the RPOD 179 as an example: HW=292, UVW=2756, CCC=1036. UVW+CCC=3792 which is exactly 292# more than the axel rating of 3500#. This is a bit fictional since it is unlikely that any weight added to the unloaded trailer will have no effect on hitch weight. Looking at the unloaded numbers: 292/2756=10.6% which is marginal but OK. If any additional weight is added exactly over the axle the tongue weight ratio would be 292/(2756+1036)=7.7% which is dangerously low. A trailer load this way will be very prone to swaying. The bottom line is added weight should and will be shared between the axle and the tongue and will result in a hitch weight significantly higher than the advertised HW number.  Many new owners do not discover this until they weight the tongue and find it much higher than expected. Loading cargo behind the axle in an attempt to minimize tongue weight is a recipe for disaster.