Ted
there are several courses in Adelaide (Australia) built on 80 acres. There are holes that are narrow, with fairways perhaps 22 yards wide, three yards of rough then a single tree line, followed by a further three yards of rough and a 22 yard wide fairway on the next hole. Very intimate in parts.
If you are going to build 18 holes on 80 acres, I expect the holes will generally be straight (because any dogleg will require more room than a straight hole, in terms of the overall property) and it is unlikely to exceed 6500 yards at the longest (less would be more feasable). Forget about a practice fairway because you can't afford the space, and make the clubhouse/greensheds/carpark etc an efficient use of land. Perhaps across the road as at Deal.
In short, it can be done, but everything needs to be planned right, and built as planned. And all land is usable (no water storage dams). Get one fairway too wide by 5 yards and you are going to have some very narrow congestion points somewhere else. A better proposition is if you have an extra 20 acres. More feasable again with an extra 40 acres.
James B