A 5 gallon recipe in a 5 gallon carboy will require a blow off tube. You will lose a little beer but it will work. With a yeast like WY 3068 you'll lose a lot of beer. WY 3068 has a very vigorous initial fermentation.
Go with the bucket. You can also tape sanitized plastic wrap over the hole for the airlock. Just poke a small hole in it for the CO2 to escape through. Most of the CO2 may escape the bucket around the rim anyway.