What do you mean by built? Rotations in the bid pack have to fall in line with the PWA, which is more restrictive than 117. Those times are also on the paperwork (PWA and max with or without extension). If you don't feel safe extending, don't extend. That's your obligation, and you (not the company) will burn if something goes wrong and you extended.

I see few instances in which my body and brain will properly handle a major aircraft malfunction on final approach after an extension to the max. I'm generally not going to take that risk and risk the safety of myself and my passengers. If BOTH crew members (I'm narrowbody) are extending, I'm definitely worried.