Bracket set-back question

[zach]

This is something I've been thinking about for a while and figured I might as well get everyones opinions. I am putting a bracket on my 20 and for power I am putting on a Merc 175 optimax. The standard bracket has a 30" set-back but I have read where people wished they had gotten a 26-28" set-back. Strick, on his beautiful restoration, built a bracket with a 25" set-back (granted he put on a v-4 engine). So here is my question, what do you think is the shortest bracket I can get and still have the Opti trim all the way up without hitting the stern of the boat?

Thanks in advance.