I thought I would post a few pictures of a trailer I just finished configuring as a combination kayak and light utility trailer (only 300 lb capacity due to very light springs). Not surprisingly, some people like using a trailer while some don’t. Some launches just aren’t good for trailers due to limited room or parking restrictions, plus you need room to store the trailer at home. But a trailer is perfect for my favorite launch and it is nice to be able to just plunk the kayak down right next to the shore.
However, I couldn’t see investing in a dedicated kayak-only trailer. It has to serve double-duty as a general purpose utility trailer too. So I have a Trailex SUT-350-S aluminum kayak trailer as the base (shortened by 3 feet), with some wood framing (last photo) to add a small flatbed, plus some removable sides of two different heights, and a lid to hide things inside. I also added some very light diagonal braces to the tongue. Before any of my modifications, I noticed that the tongue liked to flex horizontally, going into a bit of a resonance. The braces eliminated that.
Disclaimer: Trailex says don’t modify their trailers in any way or you could make them unsafe. “Not liable, warranty void, etc.” I do have to be conscious of the load limit of my one-leaf springs and keep the load properly balanced so I don’t stress the long tongue beyond a suitable tongue weight. The kayak in the pictures is 16 feet. So there’s still room for something longer plus clearance to open the hatch on the car.