I'd just get an independent LED set powered by batteries so you don't have to mess with your stock wiring.
I've actually given this considerable thought and was lucky to get a nice set of old moped aftermarket turns from jimh in his
Lend a helping hand thread.
They're battery powered & 'quick mounting' so I can remove them if I'm somewhere I won't be using them.
I DO like 'em when there's lot's of traffic.
I wanted them to look pseudo stock, as much like the stock turns on later US bikes as possible. Like this:

Only half done, the fronts are only mocked up still awaiting some ear welding & drilling, then I'll mount to the clamp bolt - but you asked today.