As for the rheostat: There's no doubt that it would be inconvenient. I suggested it because it might be an easier way to figure out the appropriate resistance.
But, thinking it through, more winds around the coil seems like the better way to do it, and the rheostat would probably just find the appropriate voltage for that particular atomizer.
Anyone have any idea what the variance is amongst atomizers? I've seen posts saying things like "801s are 3.5 Ohms" but it that +/- 0.1? Or +/-1? But I've seen other posts stating that "an 801 that's about to die will read much higher, like 12 Ohms" (or something very high). Even if a used atty has double the original resistance, isn't that half the wattage? (I have no idea - slap me stupid if an increase in resistance does not change the wattage.)
Sometimes I think that there are just so many variables that I don't understand what we're chasing.
And please note that I am not slighting your efforts here. I appreciate the heck out of them, and want to join in. But the computer QA person in me wants to eliminate all other variables, and just test the resistance of the atomizer. This means that batteries can't be used, one needs to use one juice and only one juice and all from one batch, and keep copious notes, and... Well, sometimes I just want to enjoy the vape. Life's a ..... sometimes.