Is there any assistance I can get to help my dad pay his rent in a mobile home park?

I would look for elder assistance through your state's Web site - generally under Aging Services. There should be some contact information to use as a starting point. It sound like, if he's not already, he should be on Medicaid. Good luck.
Carol

Would he consider a roommate?
Good luck.

As Carol suggested, the best place to start would be you local county Area Agency on Aging. They are a clearinghouse for resources and may be of great help in matching your dad with services available at the state, county, and even city level.

Is your father a veteran? If so look on this site or do a search for a benefit called "non-service connected basic pension". This may provide him with thousands of tax-free dollars per year.

Medicaid may also be a good possibility as all of his medical would be paid for (including his Part B premium of $96/m) freeing up money to be spent otherwise.

Rent, utility, food, and transportation assistance should all be available to him if he qualifies.