One possible way is to buy the property and take over the mortgage payments. By that I mean, you make the payments. Of course it depends on the mortgage company. I just represented a seller where the buyer (who is going to repair and flip the property) agreed in writing to make the mortgage payments. Fortunately a local bank holds the mortgage so he just goes there in person and makes the monthly payments. This might be harder to do if the mortgage company is not local. If the seller is mailing in payments and has and old style coupon book... Maybe set up a new bank account that the payments are taken out of but you put the money in.
You would absolutely want something in writing with the seller that you can sue them if they stop making mortgage payments and the house heads to foreclosure. However, usually it takes a few months before you get there so there would be plenty of notice.
As for what you might lose if it goes to foreclosure, hard to say. Would depend on the state and what it sells for. In MA, in my situation, the balance on the loan was about a third of what the house would sell for. Was bought for $500,000 balance on loan was only $167,000. Pretty sure that if it was to foreclosure it would sell for at least that much. If it sells for more, you as the "new" owner should get anything above the banks balance. You want something in writing with the seller that you can go back after the seller if you do not recoup what you have into it.
Another big concern is what happens if the bank catches wind that the property has been transferred. Most mortgages have a due on sale/transfer clause. The bank can start foreclosure even if the payments are up to date. Of course you may be able to work something out to hold them off until you complete renovations and sell or you may have to look at financing to pay off the bank. In my situation, we put it in writing that if the bank call the loan, he has 30 days to refinance or has to pay the seller and additional $25,000.
Hope that has given you some ideas for thought