In addition to the turnover cost, you have to factor in other unknowns in my opinion.  

While this wreaks of predatory issues, I don't think that you are trying to do anything intentional, you're simply seeking a solution to getting rid of a property at a profit, but the methods employed with this buyer form predatory issues by design, unknown to you until now.

My real estate agent (also an investor) suggested that I go in after close and meet each tenant and give them the opportunity right then and there to sign a new lease to bring them all up to ~$625 (that's a $75 increase for A, zero increase for B, unknown for C (I'll have to clarify), and $25 for D).

She’s willing to spend an unknown but presumably large amount of her time, as well as offer to educate you, and all she wants is your promise that if you buy a property you will allow her to make the commission.

First 2 years of college is usually common core just catching up students who might have had unknown deficiencies in high school before the focus is on the subject of the degree.I do have clients that have degrees and they mostly are doctors, tech, engineers, etc. that make close to mid six figures and some seven figures per year so the degree was worth it.

I have tried to place camera and lights but were "damaged" for unknown reasons. 

If you're dealing with a 2k all cash deal and you're going to do all the work yourself and your "handyman" has trade skills and experience with MH's you could probably do OK as long as you didn't overspend which can be almost impossible to avoid given the unknown variables that pop up at the least expected time.Additionally, if you haven't already you need to find out what the rents are and in order to determine it will give you a decent enough ROI to justify the time and money needed to purchase and refurbish the MH. 

Sorry if it came out long but my point is that there are too many unknown variables to give you an answer that will be relevant to your specific property. 

Because of that unknown and the likelihood that the market is slowing down (which we know from our realtor), I'm using $2000 as a number for avg rents.

The biggest unknown about septic systems, more specifically drain fields or lagoons associated with them, is that these need rebuilt every _________years.