Well, let me think. On my 01 Jetta AUTO, with the Draw-Tite from Etrailer (modified install) I have had a 6x10 box trailer with about 1500# of junk in it, plus the weight of Uhauls heavy-arse trailers behind my car, up and down the hills of Kentucky at 80mph without any problems. I have also pulled about 2k worth of concrete tiles on an open utility trailer... And just for giggles, I pulled an 80s Chevy half-ton out of the road (full of tools in the back) and onto the grass. But that was using the loop and a chain, not the hitch, and only at 5mph in first gear.
How did I modify the Draw-Tite install? When installing into the holes I drilled, and into the frame by the tow loop, I used all grade 8 bolts, half-inch thick, and I used 3" wide by 1/8" thick fender washers, on BOTH SIDES of the trunk pan steel, and on the driver's side shoulder steel. This makes that connection a 3" wide tiedown, instead of the 3/4" wide of just the bolt head. The instructions had NOTHING about using washers, OR using rated hardware like grade 8 bolts. Grade 8 is one tough mofo, they don't stretch or shear without extreme forces, probably stronger than the FRAME of the car.
Yea, I'm an engineer, and I over-engineer stuff I build. That's why MY house was still standing with 98% of the roof shingles intact after 3 direct-hit hurricanes in the last 2 years.