Seller Financing Negotiation Tactics and Note Selling

Hello BiggerPockets!

I come to you with a two fold question, but first I would like to present a little background. I'm attempting purchase a Mobile Home Park in MO which includes some SFR in the deal. The seller is willing to do 25% at second lien position, but fears default from me and having to take on the first position loan to preserve the property.

So BP, what are your negotiation tactics in this situation?

One thing that we had talked about is finding a note buyer during escrow who would be willing to write a letter of commitment to purchase the note at a later date, preferably after some seasoning so as to avoid SAFE laws. He referenced something called a staggered closing, and wondered if BP had any experience with such a thing.

I look forward to the responses!