Highly unlikely. Virtually all RV parks in Maine close by mid-October (many earlier than that). You're also often dealing with hard freezes past that and most parks drain and winterize their water lines when they close up.
Do be aware of the additional issue this year of either a less-than-72 hour old negative Covid-19 test result OR a mandatory self-quarantine with absolutely no shopping or dining (not even going grocery shopping) if you are visiting Maine from most other states (there are a few that are exempt from this). Also be aware the neighboring states have similar travel restrictions.