A formal probate would permit an administrator or personal rep to sell the real property asset for the benefit of the estate to generate liquidity, satisfy creditors and cost if administration, and distribute the remaining proceeds to heirs, beneficiaries and/or assignees.

But, if there is a possibility of a short fall....HOA/other debts that can't be negotiated out with the bank ( the lender will only contribute a set %) you need to be prepared to pony up some extra money above and beyond the purchase price. 

I think the advice of billing them early but giving them time to get the extra money together is a good way to proceed.

Include permit and proffessional fees.I assumed $18,000 including some of the plywood.

If 5+ acres then what is your plan for all that extra land, and do you have the money on hand and the local regulatory environment mapped out to execute that plan?

Making extra cash on the side is always fun.

It's more conservative and while my rate may be higher and I will pay a little extra in interest over time I can still accelerate my payoff.

Permits and guarantee certifications are present.

It will potentially give you some extra freedom.  

One extra measure of protection I very often take is, depending on how bad their credit score is, I take extra deposit (an extra half a month, sometimes whole).