The flame throwers tanks are from Warlords Games and are the German ones, the hose pipe coming from them is brass wire soldered on to the valve at the bottom of the tanks, then I removed the machine gun ammo cartage, drilled a hold and solders the wire in, I tend to solder every thing, but you could glue the tanks on his back , I don’t think you could glue a bit of brass wire on, but you could use the plastic sleeve from a small gauge electrical wire, you can make the straps from green stuff or just paint them in.
The flame thrower is not based on any model as such, but I dare say there were a few prototypes after the Great War, I have even seen a picture of the flamer gun looking like a rifle.