-- Last Updated: Dec-29-12 10:17 PM EST --
I have a standard boat trailer that has about the lightest suspension you normally see on such trailers. It carries a load that I think is somewhere around 400 to 500 pounds, and until I removed one leaf from each spring, it bounced terribly on any kind of "abrupt" bump, even small ones. The outboard motor used to bounce all over the place, and since the motor itself weighs 100 pounds that created a separate problem in itself. I finally got the bouncing under control though. Besides removing one leaf from each side, I built a bracket that removes all movement capability from the outboard motor's mount while in transport, and I put less pressure in the tires than recommended, so that they have about the same amount of "squat" as they would if at normal pressure when carrying the load they were actually designed for. However, running the tires with a lower pressure requires an additional modification - you must install an inner tube since they don't always remain sealed tightly to the wheel, and once you lose the seal there's no way to re-seat the tire with normal tools. The inner tube eliminates the risk of getting a non-repairable flat due to a bad seal.
Sure, you are correct that your boats won't be "beat to crap" as long as they are well secured, but I still haven't seen a trailer built from one of those kits that isn't sprung WAY stiffer than what remotely makes sense for carrying paddle craft, and they do bounce badly. It seems that people's tolerance for impracticality is inversely related to their understanding and ability to make things better, so yes, you CAN carry your boats on a 1,000-pound suspension, but plenty would chose to do it differently.
By the way, a guy in our local paddling club has a custom-built trailer for hauling multiple boats. It too is way heavier-duty than needed, but instead of the ultra-cheap, lightweight axles, tires and springs of kit trailers, it uses what I'd call a "real" trailer axle that's not made from stamped sheet metal, and the tires are as large as those found on something like a minivan, and the springs are far larger than what you see on any kit trailer. The longer leaves and progressive action of the springs provide a much smoother ride, and that combined with the relatively heavy weight of the trailer and the larger, cushier tires eliminates the problems associated with cheap trailers and their typical suspensions. It's a perfect example showing that there's more than one way to skin a cat, and that you get what you pay for.