But if I use the max load data as the starting point for my testing, as long as I look for over pressure signs I can work up from there until either A. Accuracy falls off, or Over pressure signs appear. Then back off a bit until accuracy is acceptable and over pressure signs are gone.
Is this a safe approach?
Basically, except start with the minimum recommended load and work up from there.
I usually do five rounds of a given powder weight and bump it up 0.5 grains for the next string. Mark your rounds so you know what you're working with (I use a "Sharpie" felt pen to put a unique mark - like a line, a dot, an "X" or a "V" on the primer for each string. That's handy if your ammo gets dumped.)
Record your velocities for each string and make note of excessively flattened primers, sticky extraction or velocities that are too high.
It won't take long to get the results you want.