Sure you can do that.
However, as noted below, if the owner doesn't want to sell then there's really no way to force him to.
On the other hand, people sell (and buy) mobile home parks all the time. Sometimes (rarely) it's an all-cash purchase. More often, it's done with owner financing. For example, the buyer might put 20% down, with the seller holding the note for the other 80%.
Check with a good real estate attorney. You'd need to determine a whole bunch of things: How much the park is worth (and whether you all could buy it), the appropriate legal structure (I'm guessing the residents would form a corporation and purchase the park in the name of the corporation), and so on. And, of course, you have to determine whether the owner has any interest in selling.
Hope that helps.