Well Bugman, you may not be overcapitolizing ( now that's a mouthfull ) on your rig.
Consider how long you want to keep your current boat. Long term ? Well the money spent now on a new trailer, will only give you peace -of - mind for years to come. That's good advice.
From new you can Tectyl ( rustproof ) it and the springs etc, and the thing will last for years.
If the budget requires a seconghandy, consider the price, add on the new springs, runners, axle ?,bolts,bearings, wiring. Sand blasting and re- galing or painting, and at the end of the day, you still have a secondhand trailer.
Most people don't consider that a good trailer is just as important as a good Hull, Motor, etc.
Just asking that you consider ALL the options.