I'm not sure about the bitterness, but there are recipes out there for "Sunshine pickles" or "Sunny Day pickles" and similar name variants. They call for very mature cucumbers, acknowledging even that you may have to scoop woody seeds out before making. The recipes do have onion and sugar, so that might counteract the bitterness. We made some two years ago, but our mature cucumbers were not bitter that year, so I'm not sure how they'd come out if they had been.

I remember when I was a child, Grandma would take the very big cucumbers that were turning yellow and make Senfgurken. I found a recipe here that sounds about the same:

https://www.thespruceeats.com/homemade-german-mustard-pickles-1447380

Good luck with those cucumbers!

Annie

I found another this morning. grrrrrr

If they're an heirloom variety you could save seeds from the nicest looking one.