The owner/seller can, however, control his property’s NOI (i.e. by controlling any component of NOI such as revenues, operating expenses, etc.).

You will find that those states without sales taxes have relatively high property taxes (regressive) which are impossible to avoid as one either pays them directly or as a component of rent. 

You got all your money back and can now use it on the next deal.The main component here is obviously finding a very good deal. 

Do you think it would be a huge detriment for me to purchase this fourth house and wait a year and possibly dump the two I paid cash for or cash out refi them?

I'd like to join a group that has an educational component as well.

In addition to that, banks will only finance against the "lot rent" component of rented mobile homes on land.A $150,000 Park would need about 12 homes with a lot rent of $200 per month assuming a 50% expense ratio and 10% capitalization rate.If none of this makes sense to you I would highly recommend the Mobile Home University Due Diligence Manual.  

@Jay HinrichsYes it can be called a business with a real estate component.

In our case improved operations provides the self-funding to make these investments possible, to the detriment of cash flow during the first 4-5 years, but we planned for that going in.  

It would have to be falling over significantly, mortar missing, flashing damaged, missing components, and some more just to say it needs a full replacement.I would love to get into the stories I've heard about deal killers lol but it wouldn't do me any favors.

That's a step way too many people skip to their detriment.