Runs of the length you are
Runs of the length you are doing should not be much affected by IF. And, depending on level of intensity, might not be affected at all.
I imagine you should have enough stored glycogen to complete a 4-mile run - say, 400 calories (give or take, depending on weight).
So, crazy. No.
Better runner, probably not - but, depends on your goals. If you want to train your body to burn more fat, less glycogen, you'll have to train at a fairly low heart rate (75% of max or less).
Also, keep in mind, that at a point (distance and/or intensity), running glycogen-depleted will stress the body - leading to an increase in cortisol and the related cascade of negative effects (which have been widely discussed by others much more knowledgeable than I). IMO, you're not doing yourself any favors training in such a "stressed" condition. (Which is not the same as saying it's a bad thing to push yourself - occasionally.)
I noticed that you reference Jason as a model in support of your fasting... not sure that I've seen follow-up on how that experiment worked out for him and whether he's continuing to pursue that route. I think one should take his POV and experiences - as well as those of most others - with a grain of salt while gathering as much information as possible on a subject before drawing conclusions. (Does the rest of your training match his? Are your goals similar?)
And, it should go without saying, but... the information presented here is simply my take on the matter; and, I know nothing about anything.
(MTA clarity, I hope)