The problems you hit with the idea of renting and/or lease to purchase is that now you are relying on someone else in order to make the payment on a home you are underwater in. It's not impossible, but can create more and different kinds of stress than you already have. In trying to fix the situation, you can actually be creating more possible pitfalls in your future. It's great that you are trying to think of ways to get through this, but selling your home via short sale might be the best option to take even if it puts an immediate hit on your credit.
I would consult an attorney and financial advisor before you proceed, and keep doing the homework like you are now. It never hurts to be educated in these matters.
If it wont go fha, simply try a conventional loan. Inmost cases it is only 5% down which is only $20,000 and within your budget. The only way you will be able to know what you will be able to quailify for, is to meet with a local and trusted mortgage broker, they can prequailify you at no cost, they will look at yoru credit plus your financials and let you know if there are any programs that you may quailify for.
Good luck with your mortgage
Please see my blog for more info. and tips on getting a mortgage... more