This is a disturbing thread.
Why are you in this hobby if you're not going to put the fish first? One of the reasons we keep fish is to preserve them and to educate others. Not only are you putting the individual fish at risk, but the others in your tank. What you're not getting is that you WILL have a problem in the future and you WON'T want to give the sailfin back.
If I told my LFS
that I wanted a sailfin for a 24 cube, she'd ban me from the store for a month after kicking my butt!
We give this advice from a place of knowledge and experience NOT to crush your dreams.
No one wants to spend all this money on equipment, livestock, rock, etc, only to have their tank crash one day because they made a foolish impulse buy.
Sorry to be so negative, but you've struck a nerve.
Disclaimer: I have a Yellow tang, Hippo and a Kole in my 6ft 125gal.