I have been following your build, it is going to be nice. Just looked at the pictures this morning. Jacks are out a long way and might worry about leverage on the frame. I assume that is why you want to look at the structure pics. You could run a 2" angle all the way to the top to spread the load from the jacks. One thing I am thinking about building is a quick release on the jacks. I would copy the one on this build on Rv net. .......
Page 12 of his build has the detail of the brackets.
Page 12 of his build has the detail of the brackets.