Having asset protection when coverage is denied is essential.  

I just did an analysis of 5 PM Software Tools for DIY Landlords under $20/mo.

Build a solid team and evaluate deals carefully using tools like BiggerPockets calculators to ensure strong cash flow and returns.Good luck!

Look for homes with updated systems—new plumbing, HVAC, roofing, and windows are essential for long-term value and tenant satisfaction.

I think there are two maybe 3 ways to look at this in my mind.  1) you go into it and bring it all up to modern standards but using that old charm to basically take what is there bring it up to modern standards and rent it out essentially I'm thinking cocktail bar or something trendy like that.2) most banks are on really good centrally located real estate if this is true, then I'd consider it for the dirt, plan to scrape the lot and go vertical with whatever the highest and best use is.3) a kind of combo of the two, if the lot is in a good location and its doable, pull the vaults or other "character pieces" out of the building, scrape the lot, and build whatever is best suited for the site there, but incorporate those historical pieces into the final designs.Is the site near a major retail area? 

Take a look at the BiggerPockets Market Finder tool to start looking at different markets based on your goals - https://www.biggerpockets.com/markets2.

Tools like Rentometer and BiggerPockets can help compare rental prices, and working with a CPA and attorney will ensure you structure your investments properly.

Mentorship and joint ventures are excellent ways to gain experience, and it’s essential to start small, communicate clearly, and build trust.

Refi: The piggyback HELOC is a good tool for quick access to capital, but since it's been delayed and you're already tired, it might be worth waiting for a combined refi and HELOC.

Essentially that's what you described doing, but with the added complexity of the auction process.