"I often found myself wishing I could have longer underground belts in Factorio."
I hate to beat the modding horse in to the ground, but, yeah, I'm pretty sure there are mods for this. Try searching for "belts" on the mod portal and you'll probably find a bunch that do what you want.
In my experience, whenever I've wondered if there might be a mod for something I wanted, the answer has been "yes, there already is one, and more."
It actually takes some serious creativity to come up with an interesting idea which hasn't already been turned in to a mod in Factorio.
I hate to beat the modding horse in to the ground, but, yeah, I'm pretty sure there are mods for this. Try searching for "belts" on the mod portal and you'll probably find a bunch that do what you want.
In my experience, whenever I've wondered if there might be a mod for something I wanted, the answer has been "yes, there already is one, and more."
It actually takes some serious creativity to come up with an interesting idea which hasn't already been turned in to a mod in Factorio.