When my business partner and I were still flipping we bought a couple through Auction.com and we always used a private money lender to fund those and our other flips. 

and the property had a private dwelling value appraisal much higher than the public property appraiser claims. 

This is the first time I've heard of such a thing as a land swap, especially between a municipality and a private entity.

I’m also open to exploring short-term rentals, private lending, or passive investing in funds—anything that maximizes returns while keeping risk and time commitments manageable.For context, I’d consider leaving my job if this could become a full-time venture that surpasses my current compensation (low-mid six figures).

For short-term gains, options like private lending, where your IRA acts as the lender, can provide consistent returns through interest payments.

@Geoff Engel If you don't want to be a landlord but still want to be involved with investing you could be a private money lender for flips or in partnerships and bring the money to the deal.

Before I order a second appraisal, I would investigate an alternative lender.  

@Dan GroveAs a private money lender I agree with Nicholas' sentiment.

Some lenders offer creative solutions, like a cross-collateralized loan, where they use your existing equity as security without refinancing the duplex.Another idea is partnering with private lenders or exploring a second-position mortgage, depending on your lender's terms.

Since my firm is an investor private client boutique, I do not share resources outside of my client base.