For towing 10,000 lbs, a 64mm single turbo would likely be a good choice for lowering EGTs. It should provide more airflow and keep temperatures down during heavy towing. If you want even better efficiency and response at higher power levels, a compound setup (like a stocker) can give you more power and cooler temps, but it might be a bit more complex to install and maintain.

If you're not looking to push the limits of the truck too much, a 64mm single turbo should work well for now. It gives you good towing capability while keeping things simple.