Those are the two we've used. Most of our build was complete before Tony published his book or we would have used it a lot more.
Tony's is geared to his teardrop design, while Steve's is more of a general "shop manual" with techniques for building a teardrop or small camper. (Steve also has one specifically for building his 'Rondack Lodge, which we don't have.) Steve goes into some detail on the "inside out" method of construction that (I believe) he invented, and Tony (and we) used.
I really studied Steve's book at first, particularly his epoxy/glassing techniques, as we'd never done that before. Eventually, we "graduated" away from the book as we built some confidence in our own methods.
One thing I wish I didn't copy was Steve's glassing the thin outer shell of the walls before attaching them to the skeleton. Steve did that because he was building a woodie and used several different woods to build an impressive design. However, we found the 1/8 inch Baltic birch shell lifted at the seams despite a lot of weight on the seam. We started that part over, gluing the BB to the skeleton, then laying down the epoxy and glass.
Here are my comments on Tony's book (from my Amazon review):
"This is a well written step by step guide to building a teardrop. The reader starting with this book will, with jig saw, router, and other tools commonly available to us hobbyists, be able to build a teardrop trailer just as shown on the cover. I believe the descriptions and instructions are clear, but if the reader is confused by anything, all they have to do is join the (free) forum above and ask Tony directly. This is the next best thing to having an experienced teardrop builder right there in your shop!
If you've only seen teardrops in campgrounds (as we had) and are curious, this book is a great low-cost investment to decide if a home built model should be in your future. If you've already decided to build one, materials and supplies do cost around $4000 (much less than almost any commercially built camper), and so the cost of this book is a drop in the bucket. It will more than pay for itself (in both money and time) in avoiding mistakes we first time builders are likely to make.
Tony covers the entire build, from fabricating the trailer chassis, building the (insulated) walls, floor, ceiling and roof (also insulated), and attaching them all together. His build includes cabin shelves and a headboard cabinet with sliders, which he describes in detail. He chose to build doors (rather than buy commercially made doors) and describes his design. He gives a very detailed description of the galley hatch--including the design of the hatch sides, so important for keeping the galley dry and dust free. He has chapters both on a fiberglass/epoxy exterior and aluminum. He also has chapters on the electrical system, a propane heating system, galley cabinets, and even some tips on camping. These are all from Tony's personal experience, and are written in a conversational manner that is easy to understand."
Overall, for the price of the materials and amount of labor going into a teardrop, I'd recommend buying and reading both books as a very small investment to help stir ideas and to see some good build techniques in practice.
Tom