I have decided the loft will be over the entrance and have a window (or two?) overlooking the porch. (The windows will be framed in and cut out with the router a little later.) There is a full 6′ 9″ between the floor and the loft supports.
I started by marking each stud’s top height and tacking a 1x across them all. This allowed me to push my beams up to the 1x and have the exact height correct on all of them. The 1x will be removed after all the bolts have been tightened.
Each beam is held by two 1/4″ bolts to the neighboring stud. I decided nails were not going to suffice here and lag bolts may have ‘back out’ tendencies. Each bold has a large 1 1/4 washer to prevent digging into the wood.
I was able to throw up a sheet of OSB and try it out for size. After wall panels are placed the loft will be 6′ 8″ deep and 6′ 6″ wide. There seems to be plenty of shoulder space fir side sleeping and sitting up (OK slouching) to read even after a mattress is installed.
Here is the back door. The windows will go above.