I recently got two logs from a black walnut taken down for a new house. At 30" diameter and 8 ft they are around 2500 lbs each and at the limit of my trailer. But I got them home without incident; thankfully I only had to go 2.5 miles to get them, on flat roads.
They are about the largest diameter my mill can handle and when you approach the limit everything gets harder, especially rotating it between slabbing cuts to create a cant.
But perseverance pays off and in a couple of hours I had 250 BF of almost all clear heart wood lumber.
This was the upper log. The butt log is on the mill now but at 36" some chainsaw trimming of the sides is needed for the saw carriage to clear it. That's a job for tomorrow.
John