A friend and I are trying to rent out the trailer that his grandmother used to rent out before she died just a little while ago. His family owns the trailer but the trailer park does not want us renting out the trailer because we are not of the same age as the other tenants of the park. Can the manager bar us from renting?

They can if it is an over 55 mobile home park. Otherwise no, they cannot discriminate due to your age. They can "discriminate" also against felons.

Unfortunately I just found that out while looking through 55+ Senior community laws and yes they can keep us from renting out the trailer even though his family owns the building itself.