SFI 25.5 Roll Cage Help

Ok i finally broke down and ordered my SFI 25.5C booklet for my new cage and man people were not kidding about the book being confusing and not very helpful (other than the funny car cage). I am looking for input.

Question : Can i use the stock door sill structure to attach my forward and rearward cross members and X brace the door or will i need to tie the front and rear cross member together with a tube instead of the stock sill? (note the stock floor is gone)

Also i was planning to make a tube structure around my mid plate and attach the horizontal dash bars to it. Is this allowed?