So I am in a 100mil no DH league, and as always try to minimize my innings and PAs to get the most bang for my buck.

Opening night we go into extra innings, ok not ideal.
Game 2, scored 16 runs in the 9th batting around more than twice off his tired pitchers, no starters even got to rest.
It's the worst case scenario

All my hitters, including some of my bench, who PH/PR in the extra innings affair are 20+% overused, some over 40% overused.

The staff isn't much better off, as the extra inning game and high scoring isn't helping matters.

I have a 3rd game against this opponent this evening and I'm scared to death of another mop up pitcher beatdown giving all my guys 6-7 ABs.

So how much trouble am I in, and can anything be done?

very minimal trouble unless you had too few PA to start with

1486 IP, 5610PA (not counting pitchers), playing in Wrigley, so sizable skew towards hitters

Even in Wrigley, 1486 IP and averaging 701 PA per position is more than enough for a 100 mil league

Yeah I know in the long term I will be ok, it's just short term I am a little worried, as things can spiral out of control pretty fast.
My defense is pretty solid, so that should help the staff a bit, but early extra inning games and blowouts can really put a strain on things.
I'm going to try rotating a rest schedule best I can, but my top of the order guys each had over 700PA and even they are way over projections, and of course I have no backup for them at all.

Hitting fatigue is self-correcting... it's based on PA, so as you fatigue, you perform worse and get less PA.

Pitching fatigue is the opposite and snowballs if you don't take measure to stop or control it.

Fastest and most effective way to curb pitching fatigue early on is to set a pitcher with low IP (so it doesn't take too many IP out of your bullpen), but higher IP/G as a starter with a 170/none, pull 1 PC and let them throw a CG. The extra day of rest helps all of your starters, and the CG helps your bullpen. That pitcher won't be available for roughly a weeks worth of games, but the amount they will have helped you is immense and they'll recover fine and become a useful bullpen arm again.

A nice peaceful 3-1 win was just what the doctor ordered. A few more of those and it'll all be corrected. Just have to watch some of my players closely that only had around 500-600PA.