You've asked one of three critical questions: Can the car pull the 4000# boat? Also, can the car control the 4000# tow, and can the car stop the 4000# tow?

For control, inflate all the tires up to the max shown on the tire sidewalls. That will add stability. Avoid days with strong winds.

And, the 4000# tow will put a minimum of 400 to 600# of trailer tongue weight on the car's hitch. You want no less...this relates to how far the trailer wheels are behind the tow's center of gravity, and it is essential for stability; move the trailer axle to achieve this relationship. Can the hitch and can the car's frame carry that load? It might be necessary to add a weight distribution hitch and also sway damping. (etrailer.com is a great resource. You might phone them and ask about the equipment. Some of us can buy from them after they give you good advice.) https://www.etrailer.com/dept-pg-Wei...ompatible.aspx

For braking, consider upgrading the car's brakes to something like PowerStop Z23 disc & pad upgrade kit for higher temperatures (US$315 for the parts). Absolutely get effective trailer brakes, and have the trailer brakes inspected and serviced before you tow it anywhere.

In the end, you'd be sticking your neck out. You really don't want to wreck due to an excessive tow. You can probably get away with it if you're careful, but a strong side wind can roll you over or put you into the ditch or the next lane. I wouldn't do it.