Jeez, sounds like you need a dump with all that going on internally!!! 😛 😛
1/2 inch amsteel blue gives a safe working load of 4400 lbs and max tensile strength of ~31000 lbs. with steel cable maybe go to 9/16 in, my reason for this is that with steel you can't see how strong the line is inside the swage and can become corroded and worn under the tape(if you duct tape it). If you have a super 205 then maybe go up a size. Course all depends on cycling and what your doing. I use 1/2 Amsteel on Astar as well.
Sorry don't know anything on the door gauge, but would assume it has to be in the stc for the door whether or not it has to be a tso'd gauge. By non aviation do you mean just a pressure gauge from NAPA or a gauge that is designed for door only. There are gauges for Astars that are designed for use only as a secondary gauge for external load work. Left side in a medium may be different as there may not be a easily visible gauge while flying horizontal ref unless a second one is mounted on instrument panel so the door gauge may be the primary instrument then and would think it should be approved as such. Hope it helps.
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