I have the Photo Trekker AWII, which I believe is slightly smaller than yours. I have my 4x5 wood field camera at the center bottom, oriented vertically, 90,150,210 & 300 lenses on Tech boards and Linhoff view finder. All of these items are wrapped in Calumet lens cloths, including the camera. A Minolta F spot meter in case, 6 72mm filters in the plastic boxes, 3 stepping rings, polaroid back & film, 6 filmholders and a loupe. All arranged in the compartments around the camera, This pretty much fills the main compartment. Notebook, pens, release cable, spare batteries, lens tissue, blow brush, reading glasses and center filter in the "lid". Dark cloth and 32" Photoflex reflector in the outside back pockets. Berlebach wood tripod strapped to the back.
Not much room after that!!