The only part of a stoker stove exterior that gets over 500*F in my experience is the stove body near the fire (sides and front), the rest of the areas get hot but not that hot. Even the doors are isolated by the rope gasket and the hinge connection, my doors usually measure 400*F max.
I use 500*F silicone to attach the fiberglass rope to the doors. No issues or problems with that. I also use it under the combustion fan flanges to seal and isolate for noise purposes, works great. On the Harman Magnums the fans just slide into a slot, they will back out and rattle if I don't put a small bead on each slot. The silicone has amazing adhesive qualities, I have to slice the bead to get the combustion fan out!
Of course kaowool works too.