How do I tune up this gridfinity box?  

How do I tune up this gridfinity box?

How do I start to tune up the printing for this gridfinity box?  Sometimes, it prints flawlessly across that thin bridge for the label; the rest appear like this.  They are functional once covered by a label, so I continue to print them, but I would like to tune up my settings to make them come out consistently.

The bridge is about 37mm long.  I have never trusted a bridge that long before, so this is new territory for me.  But I don't want to add interior supports, and this seems possible.

Most of the bridge is ok; it's just that trailing edge that starts to really lose its integrity.

The model I am using is here:  https://www.printables.com/model/353224-gridfinity-lite-ultra-blocks-template/files

File: GF-LITE-Flat_1x1x3_SCP_LBL.3mf

I am using a MK3S+ with a .4mm Rivo hotend, Prusament Galaxy Black PLA, and the built-in Prusament PLA profile, Default 0.20mm SPEED profile.  Setting it to QUALITY made no difference, as the bridge settings look the same.

I would like to hear how others may have solved similar problems before I start changing things.