Most people don't need to tow a boat, and those that do only need to do so a minority of the time.
People should have the option to bike to where they need to. Instead everything is basically designed around cars being the only valid form of transportation.
You don't need a truck to tow a boat either, especially not a big one. Probably nearly any motor vehicle could tow the majority of boats that are being towed, not that most people who own a truck are toeing boats and not that boats are being towed often anyway. Just rent something the one day a year you take the boat out if you need to. It'll save you money in the end.
Any medium sized boat with the ability to go fast is going to be about 5500-6500 at the bottom end. You might get one of those with an ultra light trailer but not much more. There are plenty of popular boats that you need a 3/4 ton for.
When our species develops a philosophy without the need for accumulation of wealth, a inflatable kayak will do and can be easily transported by biclycle.