The approval letter from the seller’s lender is for Only the buyer name on the purchase contract, no assignments and double closes are often prohibited. 

If the prices (even off market) for 4-units in your area are much more than $300k and that amount by itself is not enough, what I would do is look for an opportunity to do a seller-financed purchase with the owner. 

The seller most likely does not want to hire a real estate agent and pay a commission.

Many municipalities stopped providing zoning and permits to build parks years ago thats why existing parks are in such high demand little competition from new parks being built. so thats the first thing you do is go talk to the city planning department you can walk in and grab a planner at the counter to start asking your questions..

I am trying to be high tech with outbound text marketing to find motivated sellers.

This can level the playing field for individuals looking to purchase a home for personal use.Potential for Profit: Investors may find HUD properties to be lucrative investment opportunities, especially if they can acquire the property at a discounted price and make necessary improvements before selling or renting it out.Cons:Limited Availability: HUD properties are often in high demand, and competition can be fierce, particularly for properties in desirable locations or with favorable characteristics.

I'd advise against that.There's demand for STRs.

.$690k - $336k = $354kDown payment = $354k x 25% = $88.5kThe house looks like it was bought at $450k, so I am assuming that I will need to come up with around:$690k - $450k = $240k cash in addition to the down payment, Bringing the total to: $328.5k for cash to seller and as 25% down-payment based on the above.I hope I got all of the calculations correct, and honestly, the more I dive into it, the more I don't understand.

Her response was something along the lines of wait until mortgage rates are in the 5%'s and home valuations could increase by as much as 10%..When/if that happens, her argument is that sellers will be willing to relinquish their 2-3-4% rates causing inventory to increase and buyers will flood the market. 

Don’t want to be unreasonable demanding 3k two months ahead of time but also want money up front to take the property off the market.