I'm in a very similar situation to yourself: currently 220 lbs, 1994 750SX (bought it new in 1994), Skat Trak 9/17 Swirl, R&D Aquavein grate, AC Racing Aluminum -2" pole, and except for being bored out during a rebuild about 15 years ago the engine is stock and still has 150 psi in both cylinders.
I ride exclusively on the local river which sees quite a bit of boat traffic. I load in at the public boat ramp and generally work my way down the river jumping quite a variety of different sizes and shapes of boat wakes ending up about 10 miles down stream, then I head back doing a lot more of the same. I usually get apx 50-100+ jumps per tank of fuel depending on how busy the river is and what type of boats are out.
I had the same concerns as yourself with flat landings and have gotten in the habit of always landing tail in the water first, in my case I know I've got plenty of water depth so I won't bottom out. When I jump higher I usually increase the landing angle of the ski to soften the landing, but the trick to that is not going too steep of an angle or you can end up getting stripped right out of the foot tray (been there, done that). As for height of jumps, I've had other people tell me I've easily cleared 10 feet (under the ski) off the right wakes, but most common would be 3-8 feet off the water. Based on that type of regular use the only part of my ski that I've broken was the OEM fiberglass pole near the steering head, that's when I switched to the shorter aluminum pole.