My squash is just about getting ready to pick. I try to not let it get much bigger than about toilet paper tube size (okay maybe a little but I'm having trouble thinking of something the proper size). It seems that if I let the get say coke can diameter the
seeds get too hard and the outside rind/skin/whatever gets tough. But my friend from work brought me some since he was harvesting already, they were MONSTERS, even bigger than coke cans. I was thinking "oh great, these are going to be inedible" while I said thank you. Craving for yellow crookneck got the best of me and I tried them. They were great!!! Small
seeds, lots of flesh, fairly soft outside. When I ask my friend how he did it, he says nothing special,
seeds were yellow crookneck from feed store (same as mine), normal amount of water(check), grown on the ground (check). Just wondering if there is something I can do to replicate this and increase my yield by
growing bigger, edible squashes.
Maybe I have been doing something wrong all this time.
I have the same deal as you, any bigger than your description and I have always been 
Phil