The issue is that in DR a property title can only be in one name. And so if you are buying with stage payments over 5 years, you have to agree at what point you are going to transfer the title to the new owner. If you put down, say, 30% and have a loan of 70% of the value, are you expecting the owner to give you the title (and therefore confirm that you own 100% of the property)? With a charge against it of 70%, we all know that if the new owner doesn't pay the seller, it's very hard to get someone out in DR, and you would have to foreclose on them to get your money.
I'm not saying this isn't done, but I have been involved in quite a lot of property transactions in my time. This type of deal sounds attractive, but when you get into the detail, normally neither side wants to take on the risk.
In addition, if you as a buyer were asking me as a seller to let you pay over 5 years, interest free, then I am losing the interest that the sale price would have earnt over that 5 years. So basically you're asking for a big drop in price. At the moment on a peso savings certificate you can earn 10% interest per year. So over 5 years, the compound interest comes to 61%. Basically this means that if you paid me US$ 500,000 today to buy my house, and I invested that $500,000 at 10%, in 5 years the interest would come to US$ 305,000. If you're asking me to forego this interest, then you're basically asking me to sell a US$ 500,000 for US$ 195,000. Good luck if you can find an idiot who will agree to that.