I have a used construction equip trailer, 12K rated, 14 ft bed lenght with beaver tail and ramps.
The deck was shot , removed it welded in new cross braces, sand blasted, had it painted with Imron, put on new rough sawn ( for traction)white oak decking. also rebuilt brakes, bearings, spring mounts and hangers, and all new LED lites all for about $1600.
With creative loading I have no problems getting my CK20HST TLB, and either my box blade or tiller on, for approximately a 5000lb load.
As far as a tow rig I use my Dodge 2500 coversion van (makes it work) or my Ford F150 crewcab with the HD tow option, rated for 8200lb trailer, hardly know its there.