Yup, you should remove the tile and do it right. Put the sweat into it now
or you're sure to have to do it again later. Skim coats crack and don't
have good adhesion to the tiles and you have the whole issue of build up
which will require re-setting the toilet with an extension. Bite the bullet
and tear into it.



Zippertail

Peal and Stick works best with an flat surface. Is you floor flat?

1/4 inch hard board will break when I walk on it if there any gaps or
voids.
Besides your going to loose some height, which can cause other issues.

Tile comes out really easy. Big hammer and chisel, flat shovel and some
buckets or a wheel barrow.

Just how are you going to trim the toilet?