Gatorboy, we used a post hole digger, but it was before I got my tractor, so we used a gas one-man augur. I had a couple of younger guys to dig the holes, and we stretched the fence with the Cat 416 I rented to clear the fence line. I didn't have to dig all the holes; the back side had existing barbed wire. We took that down (carefully) and replaced it with the wire mesh, because the dogs could get through the barbed wire. But, we used the existing posts.
Nothing is in cement. Nothing tamped with rocks, because there aren't any rocks in this area of Florida! Just planted in the ground. It works because the corners provide their own bracing -- they're locked together tighter than a freshly wound Swiss watch (does anyone wind watches any more?). The only thing the part in the ground does is prevent them from sliding sideways when you stretch the fence. The intermediate posts don't really do anything but provide supplemental upright support for the fence -- slight exaggeration, but I think we could almost have used 1x2's for that.
The combined properties are almost 1200' long. We did use intermediate bracing every 400' that consisted of a corner setup, straightened up. In other words, the 3 7" posts are in line, with the two horizontal braces between them, and the diagonal wire going from the bottom of the center post to the tops of the outer posts. This was so we didn't have to stretch more than 400' of fence at a time.
The rolls are 330' long; we spliced them by making looping each horizontal wire around the corresponding wire on the next section, making double loops around each other, then twisting the wire back around itself. Fence pliers make the twisting really tight and moderately easy to do. It's time consuming; took me about a half hour or so to make each splice.
As for the look of the property, I like it, too, now, but I didn't when I first saw it 32 years ago (Florida scrubland, not my specific property). We're from the foothills of the Alleghenies East of Pittsburgh, and lived in Northern Massachusetts (Westford) for almost 10 years. I love the rolling NE hills, stone fences, colonial houses painted white with black shutters and a single candle in each window at Christmas, and NE churches with a simple spire. Post card beauty around every corner. Florida is flat, sandy, the slash pines are scrawny, and pepper trees are almost as bad as Kudzu. It took me a while to appreciate it. But, now, when we travel out of state, my heart quickens a little when we get to the lowlands of Georgia, and and really starts pumping as we approach the tropical zone.
Your parents live, as we do, right on the edge of that tropical zone. Look on any landscape zone map, and the tropical area is zone 10. Cape Coral, Okeechobee and Port St. Lucie are all close to the border between zones 9 & 10. To me, that's the best of both worlds -- not as intensely tropical as Miami or Naples, but not as cold as Orlando (which is too far North for anyone to live comfortably).
Cape Coral is sort of a sister city to Port St. Lucie -- similar in layout and concept. Today, they have a similar population (over 100K) and economic base. PSL is a little larger in land area (well over 700 square miles), but Cape Coral has more waterfront. Debates over the merits of the East coast of Florida vs. the West coast of Florida are as intense as hydro vs. gear, but both are great places. They're actually at the opposite ends of the same water way -- the cross-Florida waterway, which goes across Lake Okeechobee from the St. Lucie river in the East to the Caloosahatchie river in the West.
Both are also growing to large for early residents, which is why we bought in Okeechobee, and I suspect why your parents have their 5 acres on Pine Island. Do they have any plans for it?