Model Airplane News publishes a book called "Basics of R/C Model Aircraft Design". Chapter 16 specifically covers landing gear design. The book is very complete and technical. With what you are trying to do, it will probably be worth the money, especially if you intend to scratch build.

It looks to me the landing gear has two pivot joints. One at the top of the vertical strut and one at the bottom. I would guess that you actually will only need one, at the bottom. The top hinge will only rotate the wheels further backward and not absorb vertical loads. In addition, move the attachment points of the bottom shock upward on the vertical strut, and forward on the lower/horizontal strut. If you are trying to make the gear retract .... I can't even begin to figure that out. What you are trying to make is called trailing link gear, something rarely used, even on real planes, I have seen some on Navy fighters, but I cannot remember which ones.

My last recommendation would be to make up a mock up model just to test the gear.