What did he say when you asked him that?
Your idea of what is "in a position to cause damage" may differ substantially from the manager's idea.
That doesn't give you any leverage. My guess is that the manager will give you the option of signing the space lease as is or moving your MH out of the park.
South Carolina has a landlord tenant statute specific to mobile home park tenancies.
I don't see anything in there that would compel him to cut down or trim trees. If there are branches overhanging your MH you are likely going to have to trim them yourself with the consent of the manager, making sure that you do not harm or kill the trees.

