Need help poking holes in this financing set up

[Carolina Mejia]

Hi, i have a piece of property that is 1.35 acres in GA that a friend of a friend is looking to sell. Its nothing special it has an old 87' 3/2 trailer and a cement block 3/1 house both houses share utilities. The seller has a seller finance agreement with prior owner. His balloon payment is approaching in 12/2023 of $49000. It looks like he will not have the money and is looking to get out of this agreement. He wants 10 to 15k for him. Total $64000 to buy property. This was my thought, I told seller to get with the prior owner and offer him $30k cash (what i have in cash). If he takes it then we buy the property from seller like this. We get a lawyer to handle closing, we give seller 30k to pay off that loan and take old lien off property and then the seller puts a new lien on the property; he 'seller finances' the remaining 15k to me. So now the house is in our name, seller has lien- seller stays living there (he needs the 10-15k to move). Then we get with a bank to refinance or do a mortgage on the property with what it will appraise for. What i don't know is what the loan product is called? I've heard on the podcast there being 45 days to get a mortgage on a property after buying it. Once we get approved for the loan, we can pull out the funds- pay off sellers 10-15k- and depending on how much is approved get some-all-or more of our money back. I know most banks will do 80%, that should be fine. I believe the property will appraise for at least 100k. Help me poke holes; what am I missing? What due diligence steps should i take? I know the bank will do its own appraisal, however should i do an appraisal before i but the property to make sure this plan will work? The cheapest 1acre lot in the town is 39k, there is also a 2 acre lot for 39k. The cheapest property with house/trailer on it is 94k.