300g is a lot of oatmeal.

I eat Bob's Red Mill steel cut oats for breakfast every day; 1/2c dry is about 88g. That's a pretty decent meal. 3.5x that is probably most of what you eat that day.

It's quite a bit of volume, but it's "only" about 1000 Calories if it doesn't have any oils/sugar added.

I'd guess the easiest way to get it down would be to just blend the oats into water without cooking so you have something that you can just drink like water.

Yeah, the article showed that the high-dose intervention (modeled after von Noorden's famous century-old 'oat cure') is most effective. A large bowl of oatmeal (100g) all 3 meals for 2 days, 6 large bowls total.

6 weeks of 'oatmeal for breakfast every day' was less effective than 2 days of 'stuff yourself with oatmeal'.