@bryson posted the version of the corner marker/blinker that I copied, here: Corner lights as blinkers
Basically it just puts an 1157 bulb in the marker light housing, so it functions as both a marker and a blinker. I still have my signal lights underneath, so they both flash--but you'd be able to just have the one light do both functions.
After reading bit of your linked post, THIS would definitely be the way to go (in my opinion). Much simpler & standard parts (should there be any type of failure while away from home). Just a bit of wiring, after some junkyard scrounging of course. I'd be curious to know if someplace like NAPA would carry those Celica bulb sockets. It'd sure make it a little easier...