Interesting article linked below, and a cautionary one for anyone who considers buying debt in natural disaster areas where the home's value is lower than the debt.

You live in Massachusetts, and Massachusetts is a strange place for foreclosure auctions, with rather a idiosyncratic legal structure for getting things done.

As such, the plans will be largely similar in the ability to invest in anything the IRS rules allow for with checkbook control.The only real difference on the investing side is that IRA plans are subject to UDFI taxation on debt-financed real estate investments and 401k plans are not.  

Are sandwich lease options legal in MO?

I see nothing wrong with selling it, but you may want to make sure there are no legal ramifications with doing so.

Legal?

Suggested legal language for Purchase and Sale Contract: Seller and Buyer each acknowledge that in connection with Buyer’s application for approval to assume the loan(s) currently encumbering the property (the “Loan Assumption”) certain items must be delivered to __________________ [INSERT NAME OF LOAN SERVICER] (“Servicer”) so that Servicer may timely process the request for Loan Assumption.

This leaves the lender with enough wiggle room for the possibility of legal costs and holding costs with a foreclosure.

We are also seeing some multi-family being sold for appreciation and debt pay down now.  

If you mean to legally acquire the property after the tax sale that depends on the rules in the state you are investing.