That is a good point you bring up Ralph, without some kinda shoulder wrapping marabou is pretty pointless as it will just flatten out against the body of the jig or fly, but with that said for a drifted jig it would make lots of movement as the marabou would get the chanse to puff out and look rather wavey. The hobo is such the classic in terms of intruders but last year I tried some of the OPST grabboid style bunny leeches but with no luck.
As for being fragile I tend to wrap my stem a little higher up from the shoulder, tie down the point and then palmer it back while wrapping it back towards the shoulder, wire is a good idea especially if this is done near an area where fish will have their teeth on it most of the time.
This year I tried putting marabou into a dubbing loop and it seems to hold up better over a longer period of use and you can measure out the length so it can either be shorter or longer depending on preference, a bit of a pain in the my friend to do as I use a chip clip to hold the feather and then trim out what I need, then place it into the loop and spin it up.
I've seen some smaller jigs from various companies but for me they bend way to easily, I took some fairly small streamer hooks with straight eyes and made tinier bead head jigs with them cause like with your concern the #1 size jig hooks will easily damage a cutties eye or worse while a size 6 streamer hook that has been bent will do less on small fish.
I've never believed in always using smaller patterns for coho as I have laughed at how big of a spoon they will grab like a 1/2 croc or a 5/8 kit-mat spoon, and some of the flies I've gotten coho on like the bunny intruders aren't exactly pinky size but more like something that fills a 12 guage shotgun shell. But with that said twitching jigs especially with done with all marabou aren't exactly that big under the water especially when twitched fairly fast.
A friend of mine uses egg sucking leeches trailed behind a small spoon sometimes for coho, an old Gibbs croc in silver and about a foot behind he will tie in a fly and it works fairly well at times. As a guy who uses it all from fly to gear I've gone into that thought process as well and it has done fairly well for myself like with the jigs I make, a bunny streamer tied on a jig hook with a bit more flash up front, slightly heavier flies retrieved on a floating line to imitate a twitching action and so forth, I am sure others have done the same thing but not eveyone wants to spill the beans....
