Let's review:
The "off-grid" place would require you to "have utilities put in", whatever that means. So you'd be paying $400.00 a month for a bit of bare land that they'd allow you to "improve" at your own expense so that you can have basic utilities. Which you'd then be responsible to pay monthly on top of the rent. And presumably any/all such improvements would become the property of the land owner regardless of whether or not you stick around.
Right so far?
Your other choice is moving into an established Park for the same basic rent plus utilities, main difference being that you don't have to install any infrastructure yourself.
Given your lack of experience, evident youth, and presence of a dependent child, the Park option looks best to me.
This especially since winter's a comin' on!