I am thinking that the Mississippi Department of Health in that county may have the VIN because they approve the wastewater treatment plants or septic tanks.The realtor seems to be a novice and claims to have no information and 'couldn't' answer any of my questions 'because it is a foreclosure'. 

Hi Rob, Properties that are acquired with the intent to rehab/flip do not qualify for 1031 Exchange treatment. 

Next - you need to see what type of waste treatment will be required - this can vary from relatively cheap if conventional gravity fed septic can be used to CRAZY EXPENSIVE if an engineered system is required.

If so, you are in good shape and will qualify for 1031 Exchange treatment.

I'd talk to a CPA to discuss your personal situation, but in my experience, the best way to minimize taxes for these types of transactions is to minimize your FICA taxes by electing s-corp taxation treatment (either by creating an s-corp or creating an LLC taxed as an s-corp) and paying part of your gain as dividend instead of salary...If you hold the property for at least one year (without trying to sell it in that first year), you will incur long-term capital gains.If you live in the property for at least 2 out of 5 years prior to selling, you can avoid capital gains up to $500K.

You need to make these allocations between rental and residence unit because the tax treatment on the sale of your rental (investment) unit will be treated differently from the sale of your residence unit. 

Also there are no mobile homes because there are not waste treatment plants to take the waste to.  

not to mention you can save some money by tieing the septic all together of you are going to have to do a septic tank or treatment plant

But to do that you would have to have an asset in the LLC to sell and then invest it in like-kind property to get 1031 treatment and defer the taxes.  

Installment sale treatment under Section 453 allows capital gains to be deferred over the term of the note, but not depreciation recapture.