Flex fuel sensor for multiple race fuels

My situation is this:

There are two different race fuels I plan to run over time, and I'll be switching back and forth between them depending on availability.

One is more expensive, highly oxygenated, and not always available, but does make more power, this one is ethanol-free. The other is cheaper, but it's always available whenever needed, this one is 9.8% ethanol.

I planned on using a flex-fuel sensor to automatically map between them. But it turns out, the ethanol free one still reads as 11% ethanol, because the ingredients mimic ethanol by having the same dielectric constant, which is what those sensors are actually measuring.

I could just use a physical switch to tell the ecu which one we're using. But that introduces potential human error. And also doesn't cover the case of when there is a blend in the tank when switching over from one to the other.

A 1% "ethanol" swing between the two fuels seems too small to accurately blend two fuel maps, and I don't know how consistent those fuels will be from batch to batch.

Race fuels are usually advertised about how consistent their batches are. But I'm sure they still have a +/- 1% tolerance.

Looking for some creative ideas or options to deal with this?

My only advice is to put your fuel switch by the fuel filler. That is the time when you will know what fuel is going in the car. Avoid mixing by always pumping out before adding new fuel. Keep two spare empty labeled jugs for the pump out fuel of each type. Always put pumped out fuel in first when switching to a new fuel, so you'll have an empty to pump out into if you are switching back.

I would use one of these types of toggle switches, that can't be set inadvertently:

https://www.mcmaster.com/7337K97/

Yeah, that's probably what I'll end up having to do.

I've already got enough things to do before and after each race, so I was hoping for some easy button solution where I could just dump one fuel on top of the other and let the ecu do the work for me. But the more I read up, the less likely that sounds.

Another aspect to it is that the oxygenated fuel doesn't store very well. Once it's been opened and exposed to the air, it breaks down more quickly than others. Just to not waste it, I'll probably just blend it into the other fuel across multiple jugs, so it's diluted down enough to be 'close enough' and let the lambda correction handle the last of it.

Oh! One thought I did have: is there some additive or something I could add to one or the other? Anything that would drastically alter the ethanol reading enough to make a blend table work properly?

I suppose I could add in some denatured ethanol to the cheaper fuel, and get it up to E20. I'd be fine running that. And that would get me a 10% swing between the two fuels. And that's all the difference I'd have anyway if the sensor properly read 0% for the non-ethanol fuel.

Thoughts on that idea?

I know it would still add some work for us, and we'd have to be very consistent with the blending. But it would let the sensor and ecu do their job without a physical switch.