have you ever tried tech flex instead of split loom? split loom always tends to crack apart over time on me...
as far as the fasteners, you could do something with a pin spanner wrench, so it would use a threaded 'washer' type fastener like used on grinders and such to hold the discs on.
all of the other options i can think of would involve sinking the fastening device into the mounting board to allow for a flush type snap-on cover, and i'm not sure you have the thickness yet in the board for that.
come to think of it, there's the counter-sunk washers that might work:
this is called a 'Hinge Screw Washer'.. i know i've seen them in a variety of locations with different sizes what would still allow you to use a nut on the exposed bolts, might need to deep dive into a mcmaster carr to find the right size
after that, i believe they offer bolt covers that might work.