Slater
Headphoneus Supremus
I've done this for a different reason to get good fitment with a problem IEM but I'm thinking that this might help you out. Since you're not very likely to ever use a large sized tip sacrifice it to make extender rings. Turn the ear tip inside out and cut off just the portion that goes over the nozzle of the body. Cut that nozzle tube into 3 pieces (you could try 2 or 4 to change the amount of spacing). Put one of these nozzle rings into the nozzle before you put on the ear tip you want to use. This will move its opening away from the end of the nozzle but should still leave enough of the nozzle for the ear tip to stay attached properly. I've done this when I've had IEMs with a very short nozzle and needed just a bit more depth from the ear tip for good comfortable fitment but the same process seems to me to be able to solve the problem for you.
Great advice!!
Keyboard orings work perfectly too. They come 100 or more for well under $1, and are a consistent thickness. No cutting or sacrificing eartips involved