I'd elect to keep control of the table.
Others have mentioned this already and I'll agre.
Move the five in front of the the pocket. What this will do is keep him from using his 12 as a breaker and allows you to use your 5 as a breaker. Of course, he will change this situation by the time you get back to the table... but you still leave him a VERY low percentage of getting out and you controll the table by owning the pocket and having a prime breaker.
This is like a one pocket situation. You want your opponant countering your moves instead of you countering his. even though you give him room to work, you have controll of the table which puts you at the advantage.
In 8 Ball, it is not always important to get out or play the best possible safe you can. What is important is assuring you get to the table again.
If I moved the five in front of the pocket, I'd like to see anybody take the chance on getting out from there. That is what I would hope for.. you trying to get out instead of dealing with my breaker in a safe manner. If you played smart, we would be in a strategic game and - may the best man win