My Dad and I built two, one for my sister's pony barn, and one for the two car (Mom's and mine) garage.
We used the wall supported method, and while I don't remember all the dimensions (it was more'n 50 years ago) I remember the pitch, 7 to 5 for the lower section and 5 to 7 for the upper. The upper rafters were notched for the supportin' cripple wall, and the lower rafters were notched at both ends.
My danged kid brother tore down the pony barn a couple years ago, the loft was the best deer stand I ever used.