@Jay Hinrichs - maybe the defining factor is the wheeled aspect?

These are pretty fixed costs that need to be factored into the potential wholesale terms.If all of the above can be resolved and there is still a profit of 15%-25% to the buyer, and you can pay yourself a fee you believe is worth the effort, then and only then do you truly have a deal.

Another important factor to consider is the cash you have available to work with or cash you have access to because the RV parks  and mobile home parks if done right are quiet cash intensive compared to rental property.

Are you able to reinvest at a higher return after you factor in all the selling costs, income taxes and depreciation recapture?

And should not be pulled out when factoring NOI. 

I'd love to own property up there again someday, although the appreciation 'x' factor doesn't seem to exist, you should still be able to find deals that cash flow!

That amount is negotiable and will vary according to a variety of factors:  the value of the property; the motivation of the homeowner; your negotiating skills, etc. 

Let the tenant pay down the mortgage to increase equity and market appreciation to factor in.

What factors should I be looking at?

A lot of investors think that they cycle will go so well that it will eliminate their personal debt, but when you keep adding more debt to the calculation and factor in the likelihood and reality that more properties equal more problems, it's not realistic to think this way.