If your tow truck is a 1500 pickup id go with a 7K tandem axle trailer around 16ft deck,they weigh about 2000lbs,leaving you 5000lbs of capacity.That is all you really want to pull with a 1500 truck.If you go with a 2500 truck,id go up to a 9900 GVWR tandem axle,the brakes are bigger,axles much stronger,and the price isnt much more than a 7K trailer,and you will have about 7500lbs of log hauling capacity.Eithey way you want brakes on all axles,this is esp important when towing with a 1500 series truck,as they only have enough braking to stop itself,and about 1500 additional lbs,which isnt even an empty trailer.
I have 2 9900 gvwr tandems,and a 13,200gvwr dump,one of my tandems is a Starlight,very heavily built,but crude,I also have a doolittle,it is at least 500 lbs lighter than the startlight,but not nearly as beefy,both work very well for hauling logs.