@Adam R. Usually, you'll be required to disclose it to prospective residents. Yes, homeowners who have loans on their home will need flood insurance when in a flood zone per their lender. You may want to talk to your local government authority in charge of overseeing bringing homes into a park in a flood zone. They are a wealth of information. If you can talk to an inspector, even better. Survey companies are also good sources of information. Good luck!
@Adam R. often times when I speak to someone who is first exposure to a flood zone that is considered High-Risk (there is confusion & fear). The government has not done a good job educating what this means, and most of their "education" is fear based. Enhancing the problem.
If you do move forward with buying the park you could shop around and see if there is better flood coverage that may be at a better price, search private market flood.
Every property is in a flood zone. (A-zones requires flood insurance) X-zones are considered low to moderate risk although 20% of all flood claims every year come in these zones.
@Rachel H. is correct that those homeowners that have government loans will have to purchase flood insurance, this is usually can cause some buyers to shy away - especially if they go to their local or family agent who usually are generalist and only offer one option (the government option) and this can sometime be high premiums. I just want to make sure you know and anyone else that there are options out there (however i recommend working with an specialist or expert because the coverages can get a bit tricky, I think if the agent has less then 700 flood policies they are not an expert in this field.