I assume you noticed that Post #8 you referenced is 7 years old? Be careful about getting the turn signal lights too close to the headlights or they will be hard to see. I like using the add on lights like shown in Post #33 but with clear lenses. Charlie Stephens
hand signals wil work on two lane roads where you can back the traffic up before you take a righr/left ,other than that get proper size indicators.
I've used my hand the hole time,from 1959 to now. At nite I also hit brake pedal a few extra times if there no streetlights,just for extra show. I drive a 1928 Ford A,powered by V8 Thunderbird. But my son's T-bucket has them,it was a Father n Son build 10 years back now.
I found some nos side lights at an auto jumble and used some indicator bulb paint to tint the bulbs.I mounted them on the frame and they worked great... on my latest car(36) I’ve taken the reflectors out of a couple of flashlights and fitted them in the rear lights... it has really brightened them up.
I want to fabricate replacement semaphores for my '34 Austin but since they became extinct around 1960 in the European countries and were always oddities here, who would recognize that I want to make a turn?
Since you have a manual trans this might not be the answer for you. Public Transit buses use momentary switches on the floor. They look just like a dimmer switch but they are momentary. Cole Hersey has them in their catalog. You run the signals with your feet. Once you get use to it, it is great, frees up the hands. But if you have to clutch probably not for you. B
https://www.minorpartsofoxford.co.uk/morris-minor-trafficatorsemaphore/ You can still buy them new and used from here
Over here in the UK lots of folks don't understand the red flashing signals on the back of American cars as amber flashers are the norm. I used amber LEDs with a clear lens on my Merc in place of the reflectors, as they are discrete but light up real well when flashing. Because they are so small they can be hidden on an old ride quite well. Available here - https://www.carbuildersolutions.com/uk/micro-28mm-led-side-repeaters-clear-lens-amber-light-pair
Something is better than nothing. I found these kitchen track light globes at RESTORE to use as front signal lights housings. Squirted some paint and glued big truck clearance light in. I thought the globes had a Art Deco look. This is for my '40s vehicle. I am not that confident in modern drivers depending on their "lane alert, collision alert" and interpret your hand signal of right hand turn as flipping them a bird.
I'm used to using hand signals on my bobber so its a lot easier in the roadster when I don't have to use my left hand to work the clutch. Ha Ha