I'm in now way an expert on this, or have extensive experience, but just want to share my opinion to your question.Wholesaling is, in my opinion, a great way to enter the field of real estate investing, to learn what other investors look for and to find good deals that will benefit all parties involved.The problem though lies in the fact that not every person who gets started with wholesaling continues to effectively and successfully wholesale.

The property is undergoing an extensive remodel and leased out to long term tenants at market rents.

I met a guy that needed help with an extension, but he didn’t realize that it would take a significant amount of time.

File for an extension. 2.

This included reinforcing and lifting the center basement beam of a 100 year old three story house 3.5 inches (we were doing extensive cosmetic work as part of the project, so the paneling popping of the walls wasn't a big deal).

It's enough to make my hair gray So, yes, I agree with you, that trading up is the best way to go. 

You would be liable for all the damage, as Jason point out, and it could be extensive.

As we come nearer to the closing deadline, I requested a contract deadline extension from the seller which they willingly agreed/approved.

Same goes with if the owner had done extensive capital repairs that wiped out most of their cashflow, the property would still trade off of it's NOI (although the broker may try and sell you on "pro forma NOI based on the renovations). 

The closing of the replacement property must take place by the earlier of (1) 180 days from the sale of the original property, or (2) the due date (including extensions) of the tax return for the year the original property was sold