When the property is evaluated for tax purposes it is then multiplied against this factor to get the assessed value.

Depends on your state but most states treat mobile homes as personal property, titled like a car, this depending on a number of factors.

And, owner-occupants who want to live in one side of the duplex are also bidding up these properties.Consider the following factors that can make a big difference in your ROI:- What will non-homestead taxes cost you?  

Let me tell you its like pulling teeth trying to get a rate and fee quote (yes I totally understand that rates change and it is dependent on a variety of asset factors) I did find one small credit union that gave me 5.25% 80 LTV 25 year amortization, 5 year ARM, and only 0.5 point fee - problem is they are restricted to certain states.

This will be a big factor in getting a cash out refiWhat bank are you working with.  

Factor in:Tenants who may, after a short while, not able to pay the rent.

Show some newer investors why the land under can be the deciding factor.

What factors can I take into account that may assure me I would be ok, is there a population or statistic?  

Considering the neighborhood and size of the house - the two most important factors in the ultimate value of the house - and using comps and my knowledge of the local market, I figure out a "drop-dead" offer, a likely offer, and a "fire sale" offer.

I urge you to consider all factors before making an informed decision.