Here is my experience on a new 1989 boat/trailer purchase.
Our 17-foot Eliminator and trailer weighed 3250 pounds loaded with gear and gas (no people). The trailer had no brakes, but I assumed the trailer builder knew what he was doing. Then, soon after purchase, my family took a bunch of kids to the lake for the day. Approaching the lake, there was a very long steep, but straight downhill road. I literally had to push on the brake pedal so hard, that my back was pressing hard against the seatback. I almost rear-ended the car in front of me.
After this experience, I weighed the boat and trailer at 3250 pounds, which was more than 1500 pounds heavier than the California brakes requirement. . I decided to have brakes installed, which were very effective and safe, with barely a difference in drivability without trailer. During my research, I referenced the tow vehicle user's guide and found the manufacturer's trailer brake requirement is 1500 pounds or more.
In my opinion, there is no excuse to have insufficient or no brakes where needed or required by law. Do your homework so you know something about brakes on trailers and be comfortable enough to ask questions.
I found this introductory info at the following website. If anything else, if someone is asking questions like “How much can it tow?”, they need to do their homework, hopefully with a professional. https://www.rvandplaya.com/how-much-can-you-tow-without-trailer-brakes/
The amount that you can tow without trailer brakes will actually vary from state to state. However, on average you can expect from 1,500lbs in California up to 5,000lbs in Alaska.
Many other factors will determine the amount that you can tow without trailer brakes. Here below you can find the most common:
1. Pull weight
2. Weight Of Your Vehicle
3. Age of trailer
4. Speed vehicle is traveling at
5. Items Being Hauled
6. Hitch Type
7. Number of Wheels