Hi Lynn, welcome to the best teardrop forum on the net. I understand you have second thoughts about using a "CHEAP" Harbor Freight, 15 inch wheel trailer frame. Well fear not, I have built 4 trailers on such a trailer frame, and have never had a bit of trouble with any of them. My first TD has over 30,000 miles on such a set up, with never a problem what so ever. I personally feel that most TDs are constructed with much too solid materials, and they weigh too much and are heavier than necessary. I have gotten some heat from other builders, chiding me for only using 1/4 inch sidewalls and 1/8th inch roofs. However, I am convinced that pulling a 450 lb teardrop, sure beats hauling a 1200 lb unit, built with 3/4 inch walls and floor, loaded up with built-in stoves, refers, sinks and such. Light weight builds, not only greatly enhances the climbing of hillls, but greatly improves gas comsumption.
I always carry a 12 inch spare and wheel, in the event that there is a tire problem, but so far, clipping along at 65 mph, tucked in between the truckers, has worked just fine for me. As you know, the speed limit for towing a trailer in Calif is only 55 mph, and I am sure that China felt that they would eliminate any legal problems, if they added that 55mph restriction. The total weight of a HF frame in the box, is only 150 lbs, and I am sure a custom built trailer frame, springs, axle, tongue and wheels, would be much heavier. That trailer frame can be bolted together in less than 2 hours, try that on for a custom welded job.
I'm located in Wildomar, just north of the I-15 and I-215 intersection, and I invite you to swing on by and check my builds. I am always anxious to meet new builders and hopefully share some of my hard-earned building efforts. Remember, you can't just build just one, since the first one is an exploritory effort, and greater builds are sure to follow. (Just kidding). Come on by, lets talk......

Roly, the li'l ol' woody guy, in sunny So Calif.