Jerry,
I've made a good start on some of my goals, but don't expect to finish all of them, or even start all of them. Putting it out there just helps motivate me to stay on focus and get them done. Otherwise, I might get distracted and start something else that might take several years to finish.
How much was your budget for renting the excavator? It might be worth your time to buy a full sized loader backhoe. That's what I used to dig my 3/4 acre pond. I would dig so much with the hoe, then haul it off with the one yard front bucket. It took me several months of doing it this way, five days a week. I was worried about the rains coming, so I started piling up the dirt right next the the pond. Getting rid of that pile after I was done digging is what really took a long time.
After you finish digging with the backhoe, you can sell it for close to what you paid for it if you keep it in good condition. Buy 4wheel drive if you can. I have 2wd and wish I had spent the extra for 4wheel drive. Buy the newest one you can with the fewest hours. It's more money,but you will have fewer breakdowns and you'll be able to sell it for close to what you paid for it anyway.
The real expense is comparing how many hours you run it to what the price difference is when selling it compared to buying it. Fuel is a push either way. Rental fees will probably be allot more then what you depreciate the sale price when you are done.
Eddie