Since it is a mid drive, and you probably have gears on your bike,you can always downshift to make up for less torque from the motor if you limit the max current. .
I suspect your problem with the 750W BBS02 is the overly strong pedal assist. Have you changed it to increase the available settings. Mine came default with 3 levels, and level 1 would pedal me up to around 16-18 mph. I changed to to the max, which I believe is 9 levels. That dropped assist level 1 down to around 12 mph at 48V. Probably a little higher with 52V. The BBS02 has registers to adjust the assist levels if you wish to do so. I cannot comment on that process, not being much interested in changing anything in my BBS02, but I believe you can weaken the assist quite a bit for a particular level.
One of the better ways, I think, to increase range is to use PAS 0, no assist, and ride it like a bike. Use throttle as needed. My BBS02 came programmed to allow throttle in level 0, and I understand some do not. That's set with the programming cable.