[Dominik]

Again, I can only advise to see a dyno. You will see a dramatic power loss when timing is too advanced. Retard 3 deg from best value at the dyno to accommodate real live conditions (like underhood temp)

More critical is full throttle operation at medium engine speed where you have to keep an eye on your advance curve coming in too quickly. However, if this pinging is very short you can get away with it, but it is NOT recommended!
Typical example: your Winnebago going uphill at 2000rpm. Lift throttle or shift down.

And do not forget at idle speed where retarded timing can cause your headers to glow red hot in 2 minutes.

Don't fool around with this. One 1/4 mile run with wrong timing or one long back straight can cost you an engine.