Plan is I have a dcsr loan and then I have a investor that's going to pay for the remodel and then I will refinance.

Depending on your loan structure I'm not even sure you could legally offer a personal guarantee outside of the loan for that money without committing mortgage fraud, as anything that could hinder the ability of the primary lender to recover their principal is supposed to be declared during their diligence period, and any material changes up to the point of taking the loan are supposed to be disclosed as well.

If I buy a vacation home using a 2nd home loan and rent it as an AirBNB when I am not using it, can I still do a cost segregation study to accelerate depreciation and offset losses against my W2 income if I follow the rules of STR tax loophole (I.e., the average stay in the house is less than 7 days, I manage the AirBnB myself, and spend 100 hours or more a year and more time than any other person/entity on managing my AirBnB business)?

Would that affect the loan of our current property in MD? 

The caveat is also learning how to deal with appraisal contingencies when dealer with a lender that asks for this in their appraisal when the buyer is using a loan to close the deal.This is why I am trying to get out and move elsewhere in my real estate journey.

But... you made so many mistakes:(1) No Personal Guarantee: try getting a loan of credit card for an LLC.

I’m looking to owner occupy 4 unit multifamily using a VA loan.

To achieve a March 2025 multifamily property goal in Tampa, consider financing options like FHA or VA loans, local programs, and building a team.

He approached me about taking a low-interest loan from him instead of a bank.

Yes, most of the reputable lenders have a min loan amount of 65k - 75k with a minimum of 40k - 50k of that amount going toward the purchase.I've been down this road before with a few investors who want to buy cheaper homes and what I can tell you is that - 1) It's not easy and 2) You WILL NOT like the rates, fees, and points.Think about it, what does a lender stand to make on an interest only loan for about 40k.