Newbie ---- ?'s about purchasing to be owners/live-in managers

My husband and I have been discussing buying a mobile home park to live-in and manage (earning income from the park without having to work for someone else). We have lived in 4 mobile home parks and have bought and sold 4 mobile homes (making a profit on all of them). We are currently living in a mobile home that we own outright. We currently are both working outside of real estate. Our first goal is to find a mobile home park that we can purchase, that has at least a 3+/2 home that is vacant to be owner occupied, a family park (we have 5 children), in Texas or Arizona, a pool would be great (but not necessary). A fixer upper would be great as long as it has enough cash flow to cover all the expenses plus enough to cover our basic necessities until we can increase the cash flow. Been looking at postings on 2 sites for mobile home parks for sale—the asking price seems really high compared to how I’ve been reading you figure out your max purchase price. From what I’ve been reading the formula is #lots x $month rent x 12 x .6 x 10 = max purchase price (is that correct?) Is it alright to make an offer with your own finance terms to the seller? Say you figure your max and it is $240K and the seller is asking $299K. You also want the seller to finance with like $10K down and hold the note until it is 100% paid for. Would this be something that may or may not work??? All critique is greatly appreciated.

Thanks for your time.