Wondering what kind of numbers to conservatively budget for a worst case scenario?

House is worth 140k conservatively once fixed up. 

Be conservative with your numbers and you'll see how close you are to your desired cash flow.

I believe the lenders you are communicating with are not articulating this well or simply don’t want to acknowledge they are conservative and it’s easier for them to point to the amount of cash consideration you’ve invested. 

In this example the qualifying P&I rate is $5855, usually with conservative DTI (debt to income) ratios of 37-45%.

Does that seem safe/conservative enough?

I would recommend keeping your ARV conservative.

Then because it is next to and attached to a MHP deduct 15% +/- off the value of the home's appraised value.  15% may be too conservative as I have heard some say 25% or more.The Park- Two ways to play this. 

Your conservative banks will push back on LTV (basically come in at a lower number) and "claim" your in a commericial setting, but in all reality it's their standards and what they believe is commercial. 

Be conservative and connect with professionals and friends or relatives of those that have successfully invested in Real Estate.