Sounds like his goals are to save realtor fees, spread out taxes owed over time (the deal would be around 1M and he has owned them a long time and free and clear) and have an income stream without the work.

Often, it isn't real great - it's like a store credit card with high interest - but it might help spread out the cost a little. 

https://www.wycokck.org/WycoKCK/media/Neighborhood-Resource-Center/Rental%20Licensing/Documents/Rental-License-Application-Form.pdf

Basically I would own several parks spread out all over the state or region!

Namely, by not getting one lump payment for the building, but rather spreading the repayments over a number of years will the seller be protecting himself from being hit on capital gains tax?

I added the link to the spreadsheet that I generated, if anyone wants to review it:https://docs.google.com/spread...Why should real estate investors take out 30-year mortgages if the investor has to pay back nearly double to the bank, even if the investor makes profit off of the property? 

Whose to say it won't spread?

So the tax that they had been spreading out over the life of the note would then be due in full because you paid them in full. 

You can scale these prices up or down, just keep the spread between the all-in cost and ARV at 25%.

Please be sure to select a Solo 401k plan provider which allows you to take a loan and will prepare the required 401k loan documents.The repayment terms are equal monthly/quarterly payments (as you prefer) of principal and interest (e.g. prime + 1%) spread over a 5 year term (or longer if you will use the loan to purchase your primary residence).