All poly will be dead around 10 hours or so. They may not break but they either will lose tension and launch the ball or will have lost elasticity and feel flat/dead.
The longest lasting string is probably natural gut but +$$$.
Sounds like you play a lot of tennis. A stringing machine is a good investment if you do.
If you don't get a stringer, maybe Bab Tonic+ 15G or 16G gut as it will stay playable until you break it. I usually get over 20 hours before it breaks too.
A good multi might be your next option, but they tend to break faster than gut for me. NRG2 is pretty good for me.
But, sounds like a stringer might be your best bet.