Axle hub spacers - am I effectively lengthening my axle?

For a long time I’ve used these rear hub spacers: Shifter & European Go Kart Parts | Axle Parts - 50mm | Axle Wheel Hub Spacer Kit 50mm

I like them because it allows for easy width adjustments along with not having to clamp the hub so tight that I strip the bolt to keep it from moving inward.

Recently I was trying to switch between the standard length axle on my kart and a cut short axle, but I wasn’t seeing the same differences that my brother was who uses the same kart but no hub spacers. It got me thinking, since I’m filling up what would normally be empty space in the hub with 50mm rings that butt up against the inside of the hub, am I effectively lengthening any axle I use these spacers with?

As a visual in this picture:

Imagine the black portion in the hub would be open space if not using the spacers, but with the spacers they’re filled with metal which is connecting the axle all the way to the end of the hub. So am I crazy here?

To answer the next question, no I didn’t yet test out using the spacers vs not using the spacers back to back.

I never really noticed a difference in handling with or without the spacers. I guess it would depend on the materials involved. If you are running aluminum hubs and have aluminum spacers, then they may affect the flex in the hub. However if you are running magnesium hubs, then because the properties of magnesium means less flex than aluminum they are not likely to make enough of a difference to matter.

Maybe someone like @tjkoyen could shed some more light on the subject.

No, they’re fine to run without affecting relative axle length, don’t overthink it.

No, it shouldn’t and I haven’t noticed a difference. I just made my own out of soft plastic and it’s more of a backup in case the hub wants to slide. I put them in, butt the hub up against the spacers then slide it out every so slightly so the spacers are free to spin within the hub.