I know that a "subject-to" (sub-to) arrangement might work, but is there a way to release the other spouse from liability when using sub-to, or is refinancing necessary?

Kevin,That's a very vague and brief appeal.What product is being refinanced? 

I am marketing toward Subject To prospects and I have never seen this particular topic regarding refinancing sub to brought up before.

I dont want to cash-out refinance because my margins are very thin already and refinancing to a higher rate will only increase my monthly payments and negatively affect cashflow.

HELOCs offer equity without refinancing, but have variable interest rates and risk of overleveraging.

I am a licensed contractor, have a budget realtor I work with and I get my funding at 1pt and 5% and even with those advantages I am fixing, renting and refinancing because there just isn't enough profit in the fix and flip to make it worthwhile to sell.  

Great idea by not refinancing that current mortgage on your primary. 

You can always look into refinancing if rates drop later.Property Type: Multifamily properties tend to offer better cash flow than single-family homes.

We put 20-30K into a 180K property, and have refinanced it to remove all of our initial investment. 

I think that your best bet is to offer the Holder of the Contract for deed some sort of discount if they refinanced out of the contract for deed so you could get your equity, short of that I don't think you have a lot of options.