A trailer (100) is disclosed having a trailer bed (106) that may be a drop center type trailer and a frame structure extending, including a forward frame (120), rearward frame (122) and upper beam (124) therebetween. Pivotable bunk assemblies (150, 160) having left and right portions are pivotably mounted to the trailer side rails (105), the bunk portions pivotable between a deployed position extending over the trailer and a non-deployed position. A top frame (130) is hingedly attached to the upper beam and engages the bunk assemblies when it is in the closed position. Deployable, load-bearing sidewalls (102) are also optionally provided. The trailer is easily convertible between a configuration suitable for hauling logs in the deployed bunk assemblies and a configuration suitable for hauling other product--for example, wood chips or the like--with the bunk assemblies non-deployed, and the sidewalls deployed.