I'm using Arrowless Belts and think it would just make the game really shine to have that one, plus this, and the Belt Glow mod all together.
Would that be possible? :)

https://mods.factorio.com/mod/arrowless-belts

There already is an arrowless setting available. Just pick the "no arrows" option. You can use it alongside "colored rail" to distinguish belt tiers.
There are also options to turn on glowing for the arrows and/or the colored rails (if in use).
(EDIT: The other mods might override my mod. You might have to disable them for my mod to work.)

I was planning to make sprites for the thin/thick middle line too, but editing entity sprites is pretty time consuming... don't expect them too soon. :/

Probably an override thing then, thanks for the reply! :)

Update: I've managed to make up some sprites that look similar to the arrowless belt lines (the thick/thin line in the middle).
Just change the arrow style setting in the options to your liking. :)

I've also marked the "arrowless belts" and "belt glow" mods as incompatible (since what they bring is already included in BRBR). That way, these mods will need to be disabled and won't override mine.