I would send her a notice - and post it on her door in a sealed envelope - that her rent is past-due, a late charge is being assessed per the lease, and that in order to avoid eviction, she will need to remit payment now - and forever after by the 1st (or whenever) of the month. 

I know there is plenty of gray areas but a direct assessment from someone who has done both ways would be appreciated,thanks.

In some cases you may have to file in court, and possibly pay some fair easement assessment, but generally you cannot be barred from getting to your property.

I’m open to working with investors on project management, construction management, cost projections, site assessment, land preparation, foundation repair, whatever.

@David Yates, "assessed property value" meaning what the town's assessment?

I'm assuming your contract has a due-diligence clause, during which you get to assess the property and verify your assumptions before making final commitment.

They are state specific and pretty comprehensive

One that doesn’t make money on volume/quantity of piers installed, but on providing professional, honest, and accurate assessments.

We agreed on a little more than the city assessed value, for price.

@Jordan Deeney thanks Jordan for this comprehensive perspective.