I agree with Frank, I never accept as a fact any representations that realtors make about properties. There may be other reasons why the rezoning was rejected. I would discuss the matter with the local zoning authority. Also, check the comp plan to see if mobile home park zoning is a permitted use for the future. If it is then simply ask to rezone the property to comply with the future land use designation. In Florida the rule of “Strict Compliance” states that zoning must be in accordance with the comp plan.
Also, if the comp plan does not have the type of zoning you need simply request to amend the comp plan to get this particular type of zoning.
Local governments are starving for money and may be willing to listen to a developer who has a plan that will improve the community and increase their tax base.