I am building progect "LDF's Low buck truck build" just for towing. It is a 1/2 ton leaf spring truck that is going to be shortened to a SWB. I will be installing rear air bags as load lever's for when the trailer is hooked up. Also I will be doing a 5/7 drop
My car trailer is duel axel with elect brakes at each wheel and I have a good controler as well. I have the hidden hitch from ECE and it is rated at 5000lbs so that tells me 5000-6500 will be safe as long as you follow good sence while towing. If you do not have a hitch yet I highly recomend ECE's kit. Quality is top notch and it even comes with the lic plate flip up kit, reciever, mounting hardware and the plup that will go right into your truck with out cutting anything.
Kevin
LFD Inc.