This vinyl really came out great. Another option, I was pondering, is Plasti Dip spray. For years, I always thought of them as only making the rubber dip stuff for your tool handles. But, they make all kinds of products, including aerosol sprays that can later be peeled off, and all claims (with tons of video to back it up) is that it does no pain damage.
You can get a taste here:
https://www.dipyourcar.com/
I can imagine a mat black stripe that is the width of the naturally raised area on the tank. Sort of like 80's XR/XL models. My worry with all this is the same as with leaving the tank stickers on. Later, you pull it off, only to find that you paint has faded everywhere but under the stripe. Still, it is tempting...