I use a 1400 kg (2800 lbs ??) Zetor 2011 with a 5 ton (10.000 lbs ??) dumper, which started life as a Bedford truck but changed its front end, driveline, axle, cab for a solid drawbar. Both tractor and trailer are more than 40 years old. It's a bit of a pain to back it up, and you have to be careful with the clutch when you drive off, as this is a high drawbar mounted trailer.
The only thing to be cautious off, is when the dirt starts to slide out of the dumpbox, you can block both rear wheels with the brakes, but the sliding soil will just push the tractor forward untill the biggest heap of the load is dumped...
With our 3500 kg Zetor 6718 we've been pulling 20 ton silage trailers without any problem, just takes a while to get to road speed.... Off course this was with appropriate trailer brakes.