I think you are getting the horse before the cart. In two years a 13 will be 6 years old...even cheaper. How heavy a cycle are you going to put on the back? 5ers have more pin weight than they need so putting something on the back will help BUT the tires and axles are usually barely adequate so make sure it has oversized tires and axles.
This forum is the wrong place to ask about DRW and SRW as you MUST have a DRW. I often pull a gooseneck equipment trailer which weighs 20K loaded with a SRW BUT I can position the machine to where the pin is only 10-15% of the weight. I love those on here that say you cannot tow a 5er with that little pin weight...how would they know as they have never done it.:S and it handles fine in the mountains.
I hauled two dual sports on the back of my 34' 5er for several years with a SRW PU. I also position my hitch 2" behind the rear axle which is another thing you cannot do...by those that have never done it. It helps that it is a diesel crew cab long bed truck.