Would it be possible for a standalone version of this? Researchable after the default car and/or doesn't require the barrels of gas, just uses default fuels?

Nah sry.

Yeah it'd be nice if this didn't come with the bloat. Why does it need it's own fuel just for the sake of it?

I have made the decision to introduce a bit of realism with these fuels for my vehicles already long ago. On the other hand they also allow me to control the max speed of them.

But if you don't agree with my decisions, you are free to make an adjustment mod of your own which changes the fuel categories.