How many extension cords can you string together?

Assuming you have a 30 amp circuit protected by a 30 amp breaker to plug in to ....
# 10 guage hooked to the shore power cable would be just fine .
Most folks are using a # 12 guage because they are readily available at wally world , homer dee poe , and Lowes .
a # 12 guage is a 20 amp cord .
# 14 is 15 amp cord .
The # 10 are harder to find and way more expensive .
And way less flexible .