Made it work. Elected to take our chances with the heat.
Tired of comparison shopping and product research (things I tend to overdo, and probably did this time), I finally bought the Samsung 43" plasma (PN43E450). Inserting one edge into our corner-fitted television cabinet's 33.75 inches wide aperture, I placing the t.v. screen's leading edge in a corner, then raised it on two wood blocks, so I had a little room above and below. I inverted the rubber-cushioned heads on two bar-clamps, turning them into "spreaders." By putting one spreader below and one above the t.v., I managed to get the 1/3 of an inch I needed, and without bursting the cabinet (and my marriage). I then slipped the trailing edge of the t.v.'s screen through the aperture.
We live in Key Largo year-round, in a home designed to "feel" comfortable without any climate control, despite some humid 94 degree nights during summer, and a few times most years, usually in December or January, when temps get below 40 for a few consecutive days and nights. I said "feel" comfortable, but I will concede it ain't always so... there are about 5 to 15 nights each year when I would kill to have air-conditioning "right now." Of course, no one will come out and install a central air system at 9PM, so it passes.
All of our electronics generate heat, and none of them like heat. Add to that the salty air of the Florida Keys, it corrodes stuff (the cranks that open and close our awning-style windows, and the aluminum frames of our window screens go the fastest) on the windward side of the house faster than on the leeward side. Having the house open to the breezes, except during a few brief cold spells, means equipment fans that run constantly also pull a lot of dust and salty, humid air through the cooled device. That killed our desktop (tower) computers, but cooler running chip sets in newer laptops are a dream - I am working at a 2007 Dell Inspiron E1705 (17 inch screen) that practically lives outside on a screened porch.
So, keeping the 43" plasma Samsung in a closed cabinet when it is off should minimize the dust and salt exposure. opening the cabinets oak doors is required to see the screen when it is on, and that should allow for adequate ventilation. I'd be happy to install a quiet fan, but if that just trades heat for corrosion, I am not sure how to measure the trade-off.
If you have you know of any proven remedies or preventive actions that do not rely on whole house climate control systems, there are millions of us living in sub-tropical and tropical coastal environments who would love to hear them. In fact, let me recommend this as a forum topic / title: Extending the service life of electronic devices in warm (humid) coastal areas.
Thanks CNET, you have become (over several years) one of my most trusted sources for advice (along with Consumer Reports, DPReview and the bartender at... (sorry, it doesn't pay to share all your best fishing holes).