K.Z.
My nearly 4 year old son also waits until the very last minute to go potty. I will ask him several times if he needs to go while he's dancing around, wiggling, holding himself. Then he'll make a mad dash to the bathroom. Maybe it is a boy thing... But I do wonder if your son has a medical issue from reading your description of his "tiny potty accidents." Have you had him tested for infections or any other issues with his urethra or bladder?
As far as dealing with a headstrong and stubborn kid, just remember that YOU are the parent and YOU call the shots. As soon as he wakes up in the morning, take off the Pull-Up and put him in underwear. Set a timer in the house and when it goes off (every 45 minutes, every hour, you determine the time), he goes to the bathroom - no question or argument. Come up with a reward chart and give him little prizes for staying dry all day. The reward chart worked wonders with my son. He picked the prizes (one day dry was a new Matchbox car, seven days dry was going out to dinner at his favorite restaurant, etc.) and the end reward was going to Sesame Place if he stayed dry for 30 days in a row. He put a sticker on the chart if he stayed dry all day, and we hung it up where he could see it and use it as a reminder. It worked wonders with him.
It sounds like your son is using this as a hot button with you and your husband - any medical issues aside, of course - and you need to take back control. Good luck! Potty training is tough, but completely achievable!