I had a quick look at the reference files and the biggest distance between supports is about 6.5mm. That should be printable without sagging without issues.
Which slicer are you using? I’d highly recommend PrusaSlicer as it has some great features. (I’m using it with my Anycubic i3 Mega.)
Bridges should be printed slow with maximum cooling. PrusaSlicer detects the bridges and has configurable options to crank the fan speed to max and slow down the print speed. I just printed a few 100mm(!) bridges with almost no sagging.