Only trucks of C-2xx series can mount long logs addon and on some of them it seems bug as you can't straitght out trailer. C-260 seems bugged while it works fine in C-255. If you can't position yourself next to log kiosk bring 2nd truck with crane.
I did on The Island using log kiosk in SE and lumber mill in SW but you can also try this on Crossing map. Road is longer but simplier.