The first time I worked construction, I was absolutely shocked that a single weakling like me could haul around a 3x18", 60’ long plank of wood, as long as I found the center of balance and was on a flat surface. If I hadn’t done real work like that, there is no way I would believe a human could haul a tree (even a small one) by themselves.
That aside, the OP suggestion is a poor one. If you want to slow down zeds with difficult terrain, dig a pit or shallow mound. Being able to haul trunks around is useless for construction purposes. If you want to haul trunks somewhere convenient before chopping them up, it’s far easier to chop them up then load 2-3 logs into your inventory… Or use the “/” menu to move large stacks of logs… or build a draggable wooden vehicle…
It would take a ton of coding to make trunks draggable. It’s just not worth it.