Relying on Blow Off Tube to Level Out Brew

[balderdash]

I'm working on my second cider (pineapple apple from the recipe forum), but I did not leave enough head room in the carboy when I added the yeast (when I put the stopper in, it began to overflow a bit). I did not want to remove any liquid out of fear of removing too much yeast. Will I be okay relying on the blow off tube to eventually level off the excess? Is there any danger in having yeast get up around the stopper? Thanks again!