I have a TC40D with a 16LA loader and R4 tires. It's 14 ft from the front of the bucket to the back of the rear tires. I don't have a rotary mower, so I can't comment on that, but I would assume another 7 ft or so for a 6 ft mower. I doubt that the dump trailer will be practical for two reasons. Twenty feet is pretty long for a dump trailer. The empty weight would be quite high, which would limit the load capacity. I have a 12 ft dump trailer with a 10K gross capacity. It's unladen weight is about 4500 lbs, leaving 5500 lbs of load capacity. The second issue is that the bed of a dump trailer is typically quite high off the ground, compared to a regular trailer. I've carried my TC29D in mine, and I must say the ride up and down the ramps is a bit of a thrill. All of that said, I will say that a dump trailer is a really nice to have. I've had a 10,000 lb load of roots/stumps in mine. Nothing quite like pressing the button, and watching all of that come out without breaking a sweat.