Welcome to the forum. I looks like you have been bitten badly by the teardrop bug. Good for you, building a TD from scratch, and even having your 3 year old helping ol' Dad. Be sure to take pics, as you will never have another chance, at this stage in the game. Do ask any questions you want, you'll get them answered sooner than you expect. After all, we were once in the same position as you are right now. Try to touch bases with some local builders, or better yet, attend a teardrop gathering in your area. Tearjerkers are a great help, and are always willing to show you their rigs and suggest some things you haven't even thought of.
Just think, the hard part is already done, now all you have to contend with is: the size, shape, height, width, length, type of material, size and shape of windows and doors, (always have 2 doors), the layout and construction of the galley, exterior waterproof material, galley lid, electrical wiring, interior materials, a mattress, roof hatch, and all kinds of easy-to-find stuff. Good luck! Do posts pics of your build, we love pictures. Other than that, it looks like you are good to go, so let that sawdust fly.

Roly, the li'l ol' So Calif woody teardrop guy