If you did a poor job screening the tenant, it will be much easier to get rid of him or her. 

If I recall correctly, the VA is getting rid of their lending limits on Jan 1, 2020.

Does anyone have any strategies for getting rid or making a deal for a vacant lot to at least get the $49K mortgage. 

There was a thread just the other day about an investor who was stuck after numerous years with a bunch of low end units that he couldn't get rid of without taking a loss.

The land being valued higher is probably actually a bad thing because it will just mean the property taxes on it will be more while you hold it and it sits vacant (likely for a long time)  My guess is that is part of the reason the current owner wants to get rid of it.

But to get that extra $200 a month and $20k in equity you will have to: ready the property for sale by fixing any little details and making it pretty inside and out, potentially get rid of your tenants and lose out on some cashflow while it's for sale (depending on your target buyer), get professional photographers in, list it or otherwise market it and hope you actually get your $85k, then go through the not-insignificant headaches of finding an exchange property that actually gets you the 15% cash on cash and $20k in forced appreciation, close on that property and pay those costs, either do renovation yourself or hire someone to do it, get it listed for rent, and get new tenants in. 

If I move forward with the deal (as long as I renegotiate the deal for the seller to pay for all decontamination costs) will this decontamination process rid the property of being labeled as a “meth house” and allow me to sell it later if I choose to do so?

Time to rid of it and go collect sea shells on the beach 

I can't really get rid of her at this juncture since she has money tied up on this project as well. 

Getting rid of them, even if you do it yourself, is really never worth it.