The lighter you can get it registered as the cheaper it will be to licenses it each year. And, there are less regulations on lighter trailers.
But, don't be stupid about it. You could get run through a portable scale and if you do and are grossly over weight they are going to know you tried to scam the system.
But, there are certain cut off weights. (Which are at weird points) For example, I think you do not need to have brakes on a trailer until after 2900 pounds or something like that.
You really should check this out before you try to get a trailer license . It will make your live easier.