I mean, one large watermelon and a 10lb bag of potatoes already gets up over 20lbs. Add in a ton of bananas (to freeze for making ice cream), 5L bottle of vegetable oil, 4 x 1.89L of almond milk, and other food, and you get to 129lbs 😂
With cars and trucks, there comes a point at which trailer weight or the ratio of trailer weight to vehicle weight makes it unsafe without trailer brakes. Is that a consideration with bicycles?
Yes, you can get special bike trailers designed for very heavy and large loads, which come with overrun brakes. Not too common unless you're hauling stuff by bike as a business. These guys seem to even have e-assisted trailers!
You also do have to make sure that your weight bias on the bike trailer is done right.
But it feels very safe, even last night on a moderate, long downhill @ approx. 32km/h. I am slower on turns and when riding over bumps, so you do have you use caution.
I honestly just use my kid trailer, which can haul up to 100lbs/two kids. I put heavy stuff on the seats, and it conveniently has straps to keep bulky things like toilet paper from moving. Liquids and crushable things go in the panniers so they don't get punctured or crushed.
I haven't weighed my biggest loads, but I have done Costco and auto parts (e.g. battery) runs before. So for others who might have a kiddie trailer laying around, give it a shot! It's not as convenient as an actual cargo trailer, but it gets t job done.