Little Dog,
There is nothing in this world that is more fun than running a dozer, or track hoe- as long as it belongs to someone else. Whatever you rent, buy or borrow is guaranteed to break. That's when the frustration begins. Even if you don't have to pay for the repairs- the down time sucks. Especially when you have made arrangements to take off work.
I can't tell where you live, but I promise you there is a pro near you that can be in and out in a week or two and will do it for a reasonable price. The NRD office in Nebraska will provide a list of contractors that they have used to build dams in the past. They won't recommend one, but at least you will have a list to start from.
You could always rent a small backhoe or a skid loader and work on building your structure, or an island or a point.
Just my opinion, but I'd hate to see your fun ruined!
Brad B.
