If you are doing 3 12s, managing a duplex is very do-able.

As far as 30 yr fixed at 75% and 5.99% -- 75% on purchase or rate/term refinances is do-able at the moment but I would expect rates to be more so in 6.5% - 7.875% range for that product.

We wish we could afford to keep our existing home but don't think it's doable from a finance perspective.

Great to hear that it is doable.  

I'd suggest you have a KY RMLO modify the note so that it can be kept current, depending on her other credit issues this may be doable in just over two years if she cures this by paying as agreed.

It's a giant headache and if it's doable, I totally recommend folks start locally so you know what your strong and weak points are, what you need to keep an eye on in out-of-town investments, what your strategy really is (often not what you started out as), etc.  

This is doable if you have the drive to get it done.

So it's doable.

Its doable, but not just anywhere.

It's definitely doable.