This will not be pretty and is going to cost me.

Instead of having the tenants split the costs each month, it is just easier for me to do it all and charge rent accordingly. 

Even missing one component can cost you tens of thousands of dollars.

My buyer is willing to pay a few thousand over but I fear that I will be in a difficult position if they were to back out as I wouldn't have any other buyers that would be willing to purchase this contract.The agreement that I use is attached.

Aside from calling a commercial waste collection company which may be costly, is there any other solution which may cost less?

Can you recommend someone for cost segregation and a CPA in the Dallas area?

Purchased for $850k.2021 - Remodeling cost $32k2024 - Moved to a different house.

How do I protect my investment as the loan amount is more than the replacement cost of the property?

If you sell for $525k and it costs you $35k in “selling costs” (commissions, title insurance, concessions, etc.) then you need to buy $490k.

In most SFH areas the ADU adds much less value than the cost to add to the ADU.