The Sub-2 to Lease Option plan is a good and creative plan, but ideally to make it work great is to get a real cheap house sub-2, fix it up, and refinance it/re-title it to your name so you can completely control the property and equity. 

There is a specific category where you can find many discussion on this topic:https://www.biggerpockets.com/forums/51-tax-legal-...Checkbook IRA LLC is a vehicle which can give you checkbook control over your IRA, depending on your investment strategy it might be good option for you.A truly self-directed Solo 401k option that Alina mentioned above is even better alternative, however it is not for everyone.

Are you willing to give up control or not?

If you improve the property, say you go from a regular property to a temperature control unit, this will allow you to increase the monthly rents and hence drive up your revenue.  

I personally hate when wholesalers play this game and send out daisy chain properties.Wholesalers in my area do this all the time and send out each others deals, etc.I won't even work with them if they aren't in direct control of the deal with the seller.

This way you and your bookkeeper can define the scope of your engagement, you don’t get surprised by any extra “hours worked”, and you have more control over your bookkeeping costs.Everyone has different pricing for this.

Talking to them about pulling a permit to approve the work already done might let them save a bit of control and you get a legal two property building.

Right now, 15 California cities have rent control policies.

It is significantly better than SD IRA for the following reasons: Custodian is not required = no custodian fees, no asset-based fees, no transaction feesCheckbook control over your retirement fundsNo tax on leveraged real estateAbility to make large contributions: up to $61,000 annually Ability to invest tax-free using Roth account The property owned by your 401k can't be used by you personally, has to be strictly investment. 

There is no reason you can't save money if you control your spending.