🚀 go-pugleaf

In SAIL POWER by Wallace Ross, page 135, is a picture showing the
best locations for telltales on jib and main. This book has everything
in it anyone would want to know, it is a must. (Get it as a freeby
for joining the Dolphin Book Club.)
Anyway, he points out that, as you mentioned, the mast causes too much
turbulence for the telltales to be much use on the luff. He recommends
one in the middle of the sail to detect stalling, one centered high up
to show twist, and a streamer near the leech to detect separated flow
caused by bad sail shape.
Another book, which I've loaned out so I can't cite it, recommends
a streamer attached to the leech instead of two on either side in front
of it. This works for me.