You can get close with tones, but music signal is all OVER the place in both frequencies and voltages. Like, if you listen to rap, the bass line looks like somebody took a lawn mower to the top of a mountain range in a lot of songs.
I've used this table before just with a DMM measuring voltages and using the Re "net" of the subs (final ohm load to amp) to watch voltage spikes while playing songs. So like once you do that enough you can see patterns related to your voltage in the speaker wires from the amp and both Re and impedance to calculate wattage, get an idea while playing multi-toned music, you know, like you would in real life. Maybe get close with the tone, but eventually you'll have to ear tune and just know your system, because music quality is all over the place, kinda like the opposite of clean tone, in a way.
You want power (wattage) so you do V^2 (voltage) / ohm (so like 1 ohm amp load or whatever or you can measure ohms per each tone) while measuring amp voltage output, and that might be able to help you out some. It did with me before. It's more about the ratio of voltage numbers across a frequency bandwidth than the actual wattage calculation.
If your subs aren't stinking after extended play, then you're fine. Better to start low with gains and work your way up. Frequency being played can very greatly change power output/woofer stress and heat, so you gotta know your system.