While I did not get any leads yet, as feel optimistic that consistency will be key to seeing success.  

So, while I may be able to make it fly with them if I have a letter from the bank account holder (not optimistic here), it's much easier if I don't have to worry about that.

I would do my own math assuming a lower selling price and higher rehab and would want to see you had the ability to do the deal even with the less optimistic numbers.

There is reason to be optimistic.

Has this been your experience or is this overly optimistic?

Currently trying to work with some wholesalers but their rehab costs are rather optimistic...

I'm not optimistic on finance, but I'm also not giving up as I've ploughed a lot of time and a bit of money into this, and it's a deal I really want to do, and a property that I feel confident that I can turn around.

I understand that I am taking a risk by having a 40K investment in one of these homes after rehab, but with a desired sales price of say 60K am I really being that optimistic.

Maintenance and repairs will be more like %10 of gross rents in the long run, and you forgot to include property management, which is generally 10-15% of gross rents. 4% vacancy is rather optimistic as well, I would factor in at least 8%.

There is every reason to be optimistic IF YOU KNOW WHAT YOU ARE DOING!