I have a 16' 1985 Scamp that had trailing arms and a dead one at that. I replaced it with a Flexiride that I had made using the basic 3500 lb mechanicals, but with the spring rubber calibrated for 3000 lbs so that the ride would not be as harsh.
It has worked out well for me. I bought it with 10" brake drums and self adjusting brakes
with 5 lugs.
The old axle had 7" 4 lug drums and hubs and I bought new 14" wheels and tires
for a higher rating.
I set the trailer on jack stands at the height I wanted and set the angle on the Flexiride to give me that.
Also if for some reason you damage an axle or arm they are replaceable individually.