Is it ethical and legal to do a "Fixer Upper" lease?

[Will Gaston]

All:

I have a 90 year old duplex that is in very bad shape in a great location.  Some roof leaks, questionable heat, foundation issues, etc.  It's just really old and technically it might be livable, but that's about it.  My goal is is to tear this property down in January 2019 and build a new property there.  

Until then, however, I would like to get something out of it. But it makes zero sense to spend hardly anything on it, when I'm going to tear it down in 24 months. I like to take really good of my properties, but it would make more sense to let it sit vacant for two years than to spend 20-30k in Cap X.

A couple of questions:

1) Is it legal in South Carolina (or any other state) and ethical to rent the property that is in very poor shape to a handy person for a greatly reduced price? The market rate on this property is $900/month (even "As-Is") but I would rent it for say $500-$600.

2) Has anyone every done this? How do you structure a lease for a property like that? 

I'm sure somebody would rather save the $300-$400/month in paying rent and take care of any repairs, but not sure if I should do this or not.  FWIW, the property was previously rented when I bought it in it's current state.

Thanks for any advice!

[Kevin Siedlecki]

@Will Gaston - It's not gray at all. It should be very black and white. Check your local laws. They will tell you exactly what makes a unit considered livable. Usually it includes little more than working plumbing, electricity, and heat.