Any way to have these output to both sides of a belt at once and/or add more output locations? Closest I have been able to go is a blue sorter as first belt but I believe that still limits the output as full blue belts are only 45 items/second, Or am I misunderstanding things?

This may be a bit tricky to do I need to do some testing but I can answer some of your questions

1) yeah, blue belt are a bottle neck, to use the full output you need to put a chest in front of the output and then extract
2) you can full a belt by placing a splitter in front of the output, it's not a very used mechanic but you can double the output using a splitter and then join it in a single belt.

P.S. I suggest you to use a chest and a mod that add miniloader ot bots to transport the materials otherwise it's going to lose speed.

I don't see a way to use the Mantle (and Moho) without losing speed period, it outputs 5.4 cargo wagons a minute worth of ore. The Moho/Mantle would need at least 2/4 outputs with blue splitters/belts for slightly less than output capacity (or 2/4 outputs if they can output to both sides) if outputting to belts. Chest works, but there is still a massive stop/start, even with warehouse mod buildings and 14 stack inserters. I wonder if it would be better to change size/area/output/power so two miners would fill a belt of equivalent tier

well moho and mantle are more thought for modded gameplay but adding output on multiple sides should not be too hard, I'm gonna try today

Sad story short, it's impossible, mining drill actually can have only one output and it's not something I can change...

Understandable, I appreciate you taking to the time to look. I will stick to crust or eye some faster belt mods then.

I don't see a way to use the Mantle (and Moho) without losing speed period, it outputs 5.4 cargo wagons a minute worth of ore. The Moho/Mantle would need at least 2/4 outputs with blue splitters/belts for slightly less than output capacity (or 2/4 outputs if they can output to both sides) if outputting to belts. Chest works, but there is still a massive stop/start, even with warehouse mod buildings and 14 stack inserters. I wonder if it would be better to change size/area/output/power so two miners would fill a belt of equivalent tier

Mine directly into a stationary train car, then extract 10 stack inserters’ worth of throughput from the train car.

I don't see a way to use the Mantle (and Moho) without losing speed period, it outputs 5.4 cargo wagons a minute worth of ore. The Moho/Mantle would need at least 2/4 outputs with blue splitters/belts for slightly less than output capacity (or 2/4 outputs if they can output to both sides) if outputting to belts. Chest works, but there is still a massive stop/start, even with warehouse mod buildings and 14 stack inserters. I wonder if it would be better to change size/area/output/power so two miners would fill a belt of equivalent tier

Mine directly into a stationary train car, then extract 10 stack inserters’ worth of throughput from the train car.

I use a combination of AAI Containers & Warehouses & Warehousing Mod for an output box/buffer.