Moving carts/trailers with a CC is really a function of available traction. If You have ag lugged tires on dirt or dry grass they will move WAY more than You would think. Or turf tires on concrete or blacktop, same thing. But like Jerry B says, once You get into a hilly situations weight transfer takes over and can sure push You around. One afternoon when I was about ten yrs old a half-full flarebox wagon with maybe 50 bushels of oats pushed Me and the '51 M down a real steep & short hill on the back of the farm the Folks lived on for 34 yrs. The left rear wheel was NOT spinning, it was sliding on loose straw from the combine, I had the brake locked. I probably only got up to 15 mph and was able to stop without wadding the whole thing into a ball by the time I got to the big creek just beyond the bottom of the hill. Wagon & oats weighed maybe 2500#, the M maybe 5500-6000#. Took a while to get my heart out of my throat, Dad was about 200 feet away on the SM-TA running the combine watching the WHOLE thing!
Blanket statement I could agree with is if You have flat ground, then a 6X12 or so car trailer is fine to pull with a CC, even little 7 & 8 HP tractors. If You have hills or slopes then stay with something small, like a 4x8 or smaller depending on how steep the slope. I moved a LOT of Stuff at Dad's getting ready for his auction 3-1/2 yrs ago with a cart that size with my 129, even in mud & rain with turf tires.
My dump trailer is 50" wide x 70" long with 18" tall sides including the metal 12" tall sides plus the 5" tall sideboards, and when it gets a load of dirt or rock up onto the sideboards when it's hooked to the 3-pt hitch adapter on the 982 it lifts the frt wheels off the ground without any problems, even with the 50" deck still mounted. I should pull the deck & mule drive and put my 120# of suitcase weights on but it would be too long to fit in the garage then.
These little tractors are very traction limited, both on starting loads moving and stopping them safely.