Also something I forgot to mention, if you have a regular SDIRA or a QRP (including ROTH), you will have to get required minimum distribution (RMD) after a certain age (usually 70 1/2).

@Mike DymskiYou mean “you’re super fat, you should join my gym...” isn’t a great sale technique?

There is another way around the deposit that can bring to the closing, if you get the seller to agree to a second mortgage on the property with a negotiated interest rate favorable to the owner of the property, depending on the flexibility of the mortgage company and it sounds as if the mortgage company is working with a flexible lender as he is recommending you take a loan for the 20% deposit, the actual lender he is working with might accept the second mortgage as the deposit and close with you, this no money down technique works best (gets the owners on board) if you offer a decent rate on the 20%, additionally if they are in need of the funds soon but want to sell you can make the terms a very short term as I offer when I want to buy a property with this technique, offer a two year balloon payment to start, 24 months is a long time to refinance the property and now you enter my zone of leveraging (Mwwaahhahahahaha) you do a few upgrades that will improve the properties value (creative equity) I have done insane cash out loans this way (I purchased a home for $10,000 put $5,000 and the appraisal came back at 110,000, I took a 90% cash out loan and pocketed $96,000 check in my hand, remember that the property only cost me $15,000 in total, sooo....

However, when discussing how we would distribute profits, he said we would go halfers on everything, except he would charge me full price for the construction job his company does on each flip.

@Matthew Lucherini, hopefully you bought those using a self directed IRA where you won't pay tax until you take distributions.  

That said, I'm considering investing in some private companies via Debt Financing because they would pay a quarterly distribution if all goes well.I understand it can be risky (some of the private companies have a fraught history, with CEO's that were accused of fraud & bankruptcy; while other companies have a cleaner track record).

Bank foreclosures have become fairly common after Amazon closed and moved their distribution facility here. 

If you did a simple 50/50 split on both, it would mean that the two partners split all of the cash-flow each month (or quarterly or however frequently they see fit to distribute it) and then share the proceeds of the sale when it eventually sell down the road.The key to winning together is to be on the same page as much as is possible in the process. 

Per my husband, he is proposing that our property is worth the amount we'd like to turn and also that everyone in the group (if it zoned and we had a buyer) would receive an equal/ flat distribution per acre owned.

No taxes until you request a 1099-R distribution out of your IRA (unless you have a Roth).