I'm installing a basement subfloor, and am having trouble figuring out what
to do with the existing toilet hookup.

The closet flange for the toilet is set directly into the concrete and once
I add the subfloor it's obviously too low (2 1/8" to be exact). I can't
seem to find an extension kit bigger than 7/16", and supposedly you can only
stack 4 of those (leaving me short still).

I can't be the first person to do this... any suggestions other than ripping
up the concrete and extending the pipe?

Thanks!

Kevin