you are gaining valuable experience on sequence. if your fighting the bolt on the secondary, wait until you open the chaincase up. your going to miss that brake alot. comes in handy for the nut on the upper gear and the bolt on the lower gear. remember that brake on reassembly. also, be sure and not pull that brake lever while its not attached to the case and disc. you will open up another can of worms.
if you have a strap wrench, wrap it around the jackshaft. if your not worried about marring the shaft, pipe wrench or channel locks may help you if your lacking air tools or an electric impact. you can always use a 1" wrench or large crescent on the driveshaft to inhibit movement if you have extra hands available.
worst case since your stripped that far down, if you can get the bolt off the lower gear and the driveshaft removed, you can unbolt the 4 bolts on the carrier bearing for the jackshaft leaving the brake disc and clutch attached. then you would have some room to work on it.