If the neighborhood typically is slower and sells at 95% of list price...a realistic offer might be starting at 10% under list price, if it has been priced expecting a 5% below list price sale price.If the neighborhood sells at 20% more than list price, then bidding under is not a good offer.Now the circumstances surrounding any individual house could necessitate a low ball offer.

The title Amendment, which last I looked contained a reference to the original Offer, implies a modification, not a new offer or counter offer. 

That is important to understand as the incentives for modifications and delinquency and default treatments are grossly imbalanced between the two types of entities.

Any addition or modification to this Agreement must be made in writing and signed by the parties.4.

Fine, get a team of services, (lawn, cleaning, rugs, plumbing), but YOU make the decisions and assign units of work.I demand in the lease that no improvements or modifications are allowedNo subletting or roommates without an application and written permission.I give each tenant my personal cellphone and they are EXPECTED to call me for service,  not a friend nor DIY.

That's assuming you are not able to negotiate a payoff and/or some kind of loan assumption or modification.

Are there any modifications to the written lease?

A STR is a modification of a hotel room, does running a hotel seem it will work passively?

We use the same colors, the same carpet, the same trim packages, the same granite, etc (with minor modifications of course).I am not suggesting you, or anyone copy my business model.

From what I gathered, I think you are correct in this case regarding the lack of clean out access (it is an old house), thus necessitating the toilet bowl removal.