You'll have to go to a large bank and ask them what you have to do and also, what it will cost and how long it will take. A small bank probably doesn't do international commerce so they won't help you with that amount of money. You will be paying an exchange fee whether it's $10,000 or $50,0000, but if it's $50,000 I suspect you will have to pay more because it will probably be brokered by someone. A broker has to protect himself in case the value of the dollar goes the wrong way at the wrong time. Brokering it could take a few weeks so if you need the money NOW you'll be pretty anxious by the time it shows up in your bank.
Taking $10,000 across the border five times exposes you to the scrutiny of the border guards. How do they know you sold lumber instead of drugs? We went through this when we harvested in Canada. They leave no stone unturned when you have more than a few dollars on you. Jim