Be sure to put in some vacancy loss and bad debt. No property has perfect collections and at least a 5% loss should be expected on any rent you collect or utilities you bill yourself. The fact that you are already doing this on the utilities and building in some legal tells me you are anticipating some collections loss, so you should take it out of the revenue as well.
Insurance looks low. Our liability seems to run slightly higher than about $40 per lot. I’d change this to $4,500-$5,000
I would also build in a little more on the on-site management. You are doing $10 x 100 lots x 12 months and this is fine, but are you not also going to offer free housing? Additionally, our model offers manager incentives based on collections performance and leasing so we build in enough on this number to more than cover those. I use $15 per lot to be on the safe side. In essence, I would put the management closer to $22k (including the housing).
Landscaping: I don’t know a thing about Arizona, but $3k seems a little low. I guess if you have nothing but sand and no snow, you really don’t have to worry about this stuff as much.
R&M looks a little tight on a 100 lot park. It doesn’t take many sewer clogs and pot holes to hit this number and you’ve probably got over 200 people living in there. 2.5% of gross rents seems unrealistic. It should probably be at least double.
Trash: Gotta build back a collections loss on trash. Unless it’s direct billed
Electricity: You don’t own any homes yet, but you will at some point. The power will be in your name while you get it sold off. Also, are there no street lights in this park?
I certainly believe there may be unicorns out there running at 20%, but I’ve yet to see one. If I were you, I would scrutinize this thing as hard as you can to find where the hidden expenses are. You may also need to consider that the seller isn’t properly maintaining the property in an effort to get a better price. Basically, not paying for anything this year to achieve a magic NOI. So, look back through his operations as far back as you can to be sure this isn’t happening.