I have long used the tape method of FORDSVTPARTS, only my tape is called "weatherstripping tape".

Electrical tape gets gummy and black rubber can leach a dark tint deep into lighter-colored paints.

Teflon tape is very slippery.

Cloth tape can retain moisture, especially after getting dirty, which makes the cloth more hygroscopic (moisture-retaining).

Peugeot paint was very durable and impervious until the mid-1970's, but less so after that.

Find a permanent place for the bottle and then any damaged paint will never be exposed to the light of day.
I always slide the cage down to where the bottle almost touches the chain on the big ring, which also happens to be well below the downtube decals in almost every case. The bottle is still quite easy to reach.

Zefal makes plastic clamp-on mounting bosses for bottle cages, shown here (X2):