Welcome! Glad to have you here!
Ah, the elusive smoke ring! As you said, you don't want to affect the taste to get one. Makes sense, since the ring itself is tasteless; just "eye candy." I've tried the charcoal in the smoke box trick, but never got a noticeable ring.
I get a "faux" smoke ring in my pork loin brine by adding a tsp. of #1 curing salt to the 1 gallon brine. It doesn't impart any more saltiness than the regular salt brine does, and does leave a pretty cool ring. I haven't tried it on brisket yet, but plan to. Just remember, that products like Tender Quick are mostly salt, so you will be adding salt.
My "bottom line" on the smoke ring? No longer important to me at all. I have learned that the Q I can make in my SI is superior to the quality of most I've had with a smoke ring, so it's all about the taste, not the appearance. I am only judged on taste, not appearance. I think what I cook looks great, even without a smoke ring.