Linda,
The vacancy in that park is not due to mis-management. Every seller says that. The reason is that virtually no mobile homes have been sold by dealers and moved into parks in a decade. And a ton of them have been pulled out of parks due to repossession. You do not want to buy a park with less than at least 70% occupancy (really more like 80% occupancy).
Many cities have an ordinance that all new homes must be 1976 or newer (this is called a HUD code home). Some have regulations demanding 1990 or 1995 or whatever. The truth is that you will not have any homes coming into any park right now unless you buy them and bring them in yourself.
Because we want you do well, I strongly suggest that you read our books or listen to our CDs. There are many, many traps out there if you are not familiar with the industry, and an entire sub-culture of sellers and brokers who are more than happy to misinform you about everything to make a sale. We want your experience to be a pleasant and profitable one.